diff --git a/src/gprs/Makefile.am b/src/gprs/Makefile.am
index cb09979..e05eb79 100644
--- a/src/gprs/Makefile.am
+++ b/src/gprs/Makefile.am
@@ -34,6 +34,7 @@
 	$(LIBOSMOCTRL_LIBS) \
 	$(LIBOSMOGB_LIBS) \
 	$(LIBGTP_LIBS) \
+	$(LIBOSMOSIGTRAN_LIBS) \
 	$(NULL)
 
 bin_PROGRAMS = \
@@ -128,5 +129,6 @@
 	$(LIBOSMOVTY_LIBS) \
 	$(LIBCARES_LIBS) \
 	$(LIBGTP_LIBS) \
+	$(LIBOSMOSIGTRAN_LIBS) \
 	-lrt \
 	$(NULL)
diff --git a/src/gprs/sgsn_main.c b/src/gprs/sgsn_main.c
index d5d43ad..d56af0e 100644
--- a/src/gprs/sgsn_main.c
+++ b/src/gprs/sgsn_main.c
@@ -63,6 +63,8 @@
 #include <osmocom/ctrl/control_if.h>
 #include <osmocom/ctrl/ports.h>
 
+#include <osmocom/sigtran/protocol/m3ua.h>
+
 #include <gtp.h>
 
 #include "../../bscconfig.h"
@@ -326,6 +328,7 @@
 {
 	struct ctrl_handle *ctrl;
 	struct gsm_network dummy_network;
+	struct osmo_sccp_instance *sccp;
 	int rc;
 
 	srand(time(NULL));
@@ -348,6 +351,7 @@
 	osmo_stats_vty_add_cmds(&gprs_log_info);
 	sgsn_vty_init(&sgsn_inst.cfg);
 	ctrl_vty_init(tall_bsc_ctx);
+	osmo_ss7_init();
 
 	handle_options(argc, argv);
 
@@ -436,7 +440,18 @@
 	}
 
 #ifdef BUILD_IU
-	iu_init(tall_bsc_ctx, "127.0.0.2", 14001, gsm0408_gprs_rcvmsg_iu, sgsn_ranap_iu_event);
+	sccp = osmo_sccp_simple_client(tall_bsc_ctx, "OsmoSGSN",
+				       2 /* FIXME: configurable */,
+				       OSMO_SS7_ASP_PROT_M3UA, 0,
+				       "127.0.0.4" /* FIXME: configurable */,
+				       M3UA_PORT,
+				       "127.0.0.1" /* FIXME: configurable */);
+	if (!sccp) {
+		printf("Setting up SCCP client failed.\n");
+		return 8;
+	}
+
+	iu_init(tall_bsc_ctx, sccp, gsm0408_gprs_rcvmsg_iu, sgsn_ranap_iu_event);
 #endif
 
 	if (daemonize) {
diff --git a/src/libbsc/abis_rsl.c b/src/libbsc/abis_rsl.c
index 4f687a0..66cda82 100644
--- a/src/libbsc/abis_rsl.c
+++ b/src/libbsc/abis_rsl.c
@@ -2327,6 +2327,8 @@
 		DEBUGPC(DRSL, "REMOTE_PORT=%u ", port);
 		lchan->abis_ip.connect_port = port;
 	}
+
+	DEBUGPC(DRSL, "\n");
 }
 
 /*! \brief Issue IPA RSL CRCX to configure RTP on BTS side
@@ -2558,7 +2560,6 @@
 			rllh->c.msg_type);
 		break;
 	}
-	DEBUGPC(DRSL, "\n");
 
 	return rc;
 }
diff --git a/src/libbsc/bsc_vty.c b/src/libbsc/bsc_vty.c
index bd363ae..d55c6eb 100644
--- a/src/libbsc/bsc_vty.c
+++ b/src/libbsc/bsc_vty.c
@@ -57,6 +57,7 @@
 #include <openbsc/pcu_if.h>
 #include <openbsc/common_cs.h>
 #include <openbsc/vlr.h>
+#include <openbsc/handover.h>
 
 #include <inttypes.h>
 
@@ -1341,6 +1342,83 @@
 	return lchan_summary(vty, argc, argv, lchan_dump_short_vty);
 }
 
+DEFUN(show_subscr_conn,
+      show_subscr_conn_cmd,
+      "show conns",
+      SHOW_STR "Display currently active subscriber connections\n")
+{
+	struct gsm_subscriber_connection *conn;
+	struct gsm_network *net = gsmnet_from_vty(vty);
+	bool no_conns = true;
+	unsigned int count = 0;
+
+	vty_out(vty, "Active subscriber connections: %s", VTY_NEWLINE);
+
+	llist_for_each_entry(conn, &net->subscr_conns, entry) {
+		vty_out(vty, "conn nr #%u:%s", count, VTY_NEWLINE);
+		lchan_dump_full_vty(vty, conn->lchan);
+		no_conns = false;
+		count++;
+	}
+
+	if (no_conns)
+		vty_out(vty, "None%s", VTY_NEWLINE);
+
+	return CMD_SUCCESS;
+}
+
+DEFUN(handover_subscr_conn,
+      handover_subscr_conn_cmd,
+      "handover <0-255> <0-255> <0-7> LCHAN_NR <0-255>",
+      "Handover subscriber connection to other BTS\n"
+      "BTS Number (current)\n" "TRX Number\n" "Timeslot Number\n"
+      LCHAN_NR_STR "BTS Number (new)\n")
+{
+	struct gsm_network *net = gsmnet_from_vty(vty);
+	struct gsm_subscriber_connection *conn;
+	struct gsm_bts *bts;
+	struct gsm_bts *new_bts = NULL;
+	unsigned int bts_nr = atoi(argv[0]);
+	unsigned int trx_nr = atoi(argv[1]);
+	unsigned int ts_nr = atoi(argv[2]);
+	unsigned int ss_nr = atoi(argv[3]);
+	unsigned int bts_nr_new = atoi(argv[4]);
+
+	/* Lookup the BTS where we want to handover to */
+	llist_for_each_entry(bts, &net->bts_list, list) {
+		if (bts->nr == bts_nr_new) {
+			new_bts = bts;
+			break;
+		}
+	}
+
+	if (!new_bts) {
+		vty_out(vty, "Unable to trigger handover,"
+			"specified bts #%u does not exist %s", bts_nr_new,
+			VTY_NEWLINE);
+		return CMD_WARNING;
+	}
+
+	/* Find the connection/lchan that we want to handover */
+	llist_for_each_entry(conn, &net->subscr_conns, entry) {
+		if (conn->bts->nr == bts_nr &&
+		    conn->lchan->ts->trx->nr == trx_nr &&
+		    conn->lchan->ts->nr == ts_nr && conn->lchan->nr == ss_nr) {
+			vty_out(vty, "starting handover for lchan %s...%s",
+				conn->lchan->name, VTY_NEWLINE);
+			lchan_dump_full_vty(vty, conn->lchan);
+			bsc_handover_start(conn->lchan, new_bts);
+			return CMD_SUCCESS;
+		}
+	}
+
+	vty_out(vty, "Unable to trigger handover,"
+		"specified connection (bts=%u,trx=%u,ts=%u,ss=%u) does not exist%s",
+		bts_nr, trx_nr, ts_nr, ss_nr, VTY_NEWLINE);
+
+	return CMD_WARNING;
+}
+
 static void paging_dump_vty(struct vty *vty, struct gsm_paging_request *pag)
 {
 	vty_out(vty, "Paging on BTS %u%s", pag->bts->nr, VTY_NEWLINE);
@@ -4153,6 +4231,9 @@
 	install_element_ve(&show_lchan_cmd);
 	install_element_ve(&show_lchan_summary_cmd);
 
+	install_element_ve(&show_subscr_conn_cmd);
+	install_element_ve(&handover_subscr_conn_cmd);
+
 	install_element_ve(&show_paging_cmd);
 	install_element_ve(&show_paging_group_cmd);
 
diff --git a/src/libbsc/handover_logic.c b/src/libbsc/handover_logic.c
index 57d1dcd..14566cf 100644
--- a/src/libbsc/handover_logic.c
+++ b/src/libbsc/handover_logic.c
@@ -101,7 +101,8 @@
 	if (bsc_ho_by_old_lchan(old_lchan))
 		return -EBUSY;
 
-	DEBUGP(DHO, "(old_lchan on BTS %u, new BTS %u)\n",
+	DEBUGP(DHO, "Beginning with handover operation"
+	       "(old_lchan on BTS %u, new BTS %u) ...\n",
 		old_lchan->ts->trx->bts->nr, bts->nr);
 
 	rate_ctr_inc(&bts->network->bsc_ctrs->ctr[BSC_CTR_HANDOVER_ATTEMPTED]);
diff --git a/src/libcommon-cs/Makefile.am b/src/libcommon-cs/Makefile.am
index f3921ba..21c2745 100644
--- a/src/libcommon-cs/Makefile.am
+++ b/src/libcommon-cs/Makefile.am
@@ -16,5 +16,6 @@
 noinst_LIBRARIES = libcommon-cs.a
 
 libcommon_cs_a_SOURCES = \
+	a_reset.c \
 	common_cs.c \
 	common_cs_vty.c
diff --git a/src/libcommon-cs/a_reset.c b/src/libcommon-cs/a_reset.c
new file mode 100644
index 0000000..c0294c7
--- /dev/null
+++ b/src/libcommon-cs/a_reset.c
@@ -0,0 +1,224 @@
+/* (C) 2017 by sysmocom s.f.m.c. GmbH
+ * All Rights Reserved
+ *
+ * Author: Philipp Maier
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include <osmocom/core/logging.h>
+#include <osmocom/core/utils.h>
+#include <osmocom/core/timer.h>
+#include <osmocom/core/fsm.h>
+#include <unistd.h>
+#include <errno.h>
+#include <string.h>
+#include <openbsc/debug.h>
+#include <openbsc/bsc_msc_data.h>
+#include <openbsc/osmo_bsc_sigtran.h>
+
+#define RESET_RESEND_INTERVAL 2	/* sec */
+#define RESET_RESEND_TIMER_NO 1234	/* FIXME: dig out the real timer number */
+#define BAD_CONNECTION_THRESOLD 3	/* connection failures */
+
+enum fsm_states {
+	ST_DISC,		/* Disconnected from remote end */
+	ST_CONN,		/* We have a confirmed connection */
+};
+
+static const struct value_string fsm_state_names[] = {
+	{ST_DISC, "ST_DISC (disconnected)"},
+	{ST_CONN, "ST_CONN (connected)"},
+	{0, NULL},
+};
+
+enum fsm_evt {
+	EV_RESET_ACK,		/* got reset acknowlegement from remote end */
+	EV_N_DISCONNECT,	/* lost a connection */
+	EV_N_CONNECT,		/* made a successful connection */
+};
+
+static const struct value_string fsm_evt_names[] = {
+	{EV_RESET_ACK, "EV_RESET_ACK"},
+	{EV_N_DISCONNECT, "EV_N_DISCONNECT"},
+	{EV_N_CONNECT, "EV_N_CONNECT"},
+	{0, NULL},
+};
+
+/* Disconnected state */
+static void fsm_disc_cb(struct osmo_fsm_inst *fi, uint32_t event, void *data)
+{
+	struct a_reset_ctx *reset = (struct a_reset_ctx *)data;
+	OSMO_ASSERT(reset);
+
+	LOGP(DMSC, LOGL_NOTICE, "(%s) fsm-state (msc-reset): %s, fsm-event: %s\n", reset->name,
+	     get_value_string(fsm_state_names, ST_CONN), get_value_string(fsm_evt_names, event));
+
+	reset->conn_loss_counter = 0;
+	osmo_fsm_inst_state_chg(fi, ST_CONN, 0, 0);
+}
+
+/* Connected state */
+static void fsm_conn_cb(struct osmo_fsm_inst *fi, uint32_t event, void *data)
+{
+	struct a_reset_ctx *reset = (struct a_reset_ctx *)data;
+	OSMO_ASSERT(reset);
+
+	LOGP(DMSC, LOGL_NOTICE, "(%s) fsm-state (msc-reset): %s, fsm-event: %s\n", reset->name,
+	     get_value_string(fsm_state_names, ST_CONN), get_value_string(fsm_evt_names, event));
+
+	switch (event) {
+	case EV_N_DISCONNECT:
+		if (reset->conn_loss_counter >= BAD_CONNECTION_THRESOLD) {
+			LOGP(DMSC, LOGL_NOTICE, "(%s) SIGTRAN connection down, reconnecting...\n", reset->name);
+			osmo_fsm_inst_state_chg(fi, ST_DISC, RESET_RESEND_INTERVAL, RESET_RESEND_TIMER_NO);
+		} else
+			reset->conn_loss_counter++;
+		break;
+	case EV_N_CONNECT:
+		reset->conn_loss_counter = 0;
+		break;
+	}
+}
+
+/* Timer callback to retransmit the reset signal */
+static int fsm_reset_ack_timeout_cb(struct osmo_fsm_inst *fi)
+{
+	struct a_reset_ctx *reset = (struct a_reset_ctx *)fi->priv;
+
+	LOGP(DMSC, LOGL_NOTICE, "(%s) reset-ack timeout (T%i) in state %s, resending...\n", reset->name, fi->T,
+	     get_value_string(fsm_state_names, fi->state));
+
+	reset->cb(reset->priv);
+
+	osmo_fsm_inst_state_chg(fi, ST_DISC, RESET_RESEND_INTERVAL, RESET_RESEND_TIMER_NO);
+	return 0;
+}
+
+static struct osmo_fsm_state fsm_states[] = {
+	[ST_DISC] = {
+		     .in_event_mask = (1 << EV_RESET_ACK),
+		     .out_state_mask = (1 << ST_DISC) | (1 << ST_CONN),
+		     .name = "DISC",
+		     .action = fsm_disc_cb,
+		     },
+	[ST_CONN] = {
+		     .in_event_mask = (1 << EV_N_DISCONNECT) | (1 << EV_N_CONNECT),
+		     .out_state_mask = (1 << ST_DISC) | (1 << ST_CONN),
+		     .name = "CONN",
+		     .action = fsm_conn_cb,
+		     },
+};
+
+/* State machine definition */
+static struct osmo_fsm fsm = {
+	.name = "FSM RESET",
+	.states = fsm_states,
+	.num_states = ARRAY_SIZE(fsm_states),
+	.log_subsys = DMSC,
+	.timer_cb = fsm_reset_ack_timeout_cb,
+};
+
+/* Create and start state machine which handles the reset/reset-ack procedure */
+struct a_reset_ctx *a_reset_alloc(const void *ctx, const char *name, void *cb, void *priv)
+{
+	OSMO_ASSERT(name);
+
+	struct a_reset_ctx *reset;
+
+	/* Register the fsm description (if not already done) */
+	if (osmo_fsm_find_by_name(fsm.name) != &fsm)
+		osmo_fsm_register(&fsm);
+
+	/* Allocate and configure a new fsm instance */
+	reset = talloc_zero(ctx, struct a_reset_ctx);
+	OSMO_ASSERT(reset);
+	reset->priv = priv;
+	reset->cb = cb;
+	strncpy(reset->name, name, sizeof(reset->name));
+	reset->conn_loss_counter = 0;
+	reset->fsm = osmo_fsm_inst_alloc(&fsm, NULL, NULL, LOGL_DEBUG, "FSM RESET INST");
+	OSMO_ASSERT(reset->fsm);
+	reset->fsm->priv = reset;
+	LOGP(DMSC, LOGL_NOTICE, "(%s) reset handler fsm created.\n", reset->name);
+
+	/* kick off reset-ack sending mechanism */
+	osmo_fsm_inst_state_chg(reset->fsm, ST_DISC, RESET_RESEND_INTERVAL, RESET_RESEND_TIMER_NO);
+
+	return reset;
+}
+
+/* Tear down state machine */
+void a_reset_free(struct a_reset_ctx *reset)
+{
+	OSMO_ASSERT(reset);
+	OSMO_ASSERT(reset->fsm);
+
+	osmo_fsm_inst_free(reset->fsm);
+	reset->fsm = NULL;
+
+	memset(reset, 0, sizeof(*reset));
+	talloc_free(reset);
+
+	LOGP(DMSC, LOGL_NOTICE, "(%s) reset handler fsm destroyed.\n", reset->name);
+}
+
+/* Confirm that we sucessfully received a reset acknowlege message */
+void a_reset_ack_confirm(struct a_reset_ctx *reset)
+{
+	OSMO_ASSERT(reset);
+	OSMO_ASSERT(reset->fsm);
+
+	osmo_fsm_inst_dispatch(reset->fsm, EV_RESET_ACK, reset);
+}
+
+/* Report a failed connection */
+void a_reset_conn_fail(struct a_reset_ctx *reset)
+{
+	/* If no reset context is supplied, just drop the info */
+	if (!reset)
+		return;
+
+	OSMO_ASSERT(reset->fsm);
+
+	osmo_fsm_inst_dispatch(reset->fsm, EV_N_DISCONNECT, reset);
+}
+
+/* Report a successful connection */
+void a_reset_conn_success(struct a_reset_ctx *reset)
+{
+	/* If no reset context is supplied, just drop the info */
+	if (!reset)
+		return;
+
+	OSMO_ASSERT(reset->fsm);
+
+	osmo_fsm_inst_dispatch(reset->fsm, EV_N_CONNECT, reset);
+}
+
+/* Check if we have a connection to a specified msc */
+bool a_reset_conn_ready(struct a_reset_ctx *reset)
+{
+	/* If no reset context is supplied, we assume that
+	 * the connection can't be ready! */
+	if (!reset)
+		return false;
+
+	OSMO_ASSERT(reset->fsm);
+	if (reset->fsm->state == ST_CONN)
+		return true;
+
+	return false;
+}
diff --git a/src/libcommon-cs/common_cs.c b/src/libcommon-cs/common_cs.c
index 99206c8..d6dff95 100644
--- a/src/libcommon-cs/common_cs.c
+++ b/src/libcommon-cs/common_cs.c
@@ -78,6 +78,8 @@
 
 	net->dyn_ts_allow_tch_f = true;
 
+	INIT_LLIST_HEAD(&net->a.bscs);
+
 	return net;
 }
 
diff --git a/src/libcommon/common_vty.c b/src/libcommon/common_vty.c
index 6e1c10b..1443791 100644
--- a/src/libcommon/common_vty.c
+++ b/src/libcommon/common_vty.c
@@ -34,6 +34,7 @@
 #include <osmocom/vty/command.h>
 #include <osmocom/vty/buffer.h>
 #include <osmocom/vty/vty.h>
+#include <osmocom/sigtran/osmo_ss7.h>
 
 
 int bsc_vty_go_parent(struct vty *vty)
@@ -117,13 +118,15 @@
 	case MSC_NODE:
 	case MNCC_INT_NODE:
 	case NITB_NODE:
-	default:
-		if (bsc_vty_is_config_node(vty, vty->node))
-			vty->node = CONFIG_NODE;
-		else
-			vty->node = ENABLE_NODE;
-
+		vty->node = CONFIG_NODE;
 		vty->index = NULL;
+		break;
+	case SUBSCR_NODE:
+		vty->node = ENABLE_NODE;
+		vty->index = NULL;
+		break;
+	default:
+		osmo_ss7_vty_go_parent(vty);
 	}
 
 	return vty->node;
@@ -131,6 +134,11 @@
 
 int bsc_vty_is_config_node(struct vty *vty, int node)
 {
+	/* Check if libosmo-sccp declares the node in
+	 * question as config node */
+	if (osmo_ss7_is_config_node(vty, node))
+		return 1;
+
 	switch (node) {
 	/* add items that are not config */
 	case OML_NODE:
diff --git a/src/libcommon/debug.c b/src/libcommon/debug.c
index 7dbbc6a..7236413 100644
--- a/src/libcommon/debug.c
+++ b/src/libcommon/debug.c
@@ -189,6 +189,12 @@
 		.description = "Iu-CS Protocol",
 		.enabled = 1, .loglevel = LOGL_DEBUG,
 	},
+	[DSIGTRAN] = {
+		.name = "DSIGTRAN",
+		.description = "SIGTRAN Signalling Transport",
+		.color = "\033[1;29m",
+		.enabled = 1, .loglevel = LOGL_DEBUG,
+	},
 };
 
 static int filter_fn(const struct log_context *ctx, struct log_target *tar)
diff --git a/src/libiu/iu.c b/src/libiu/iu.c
index 5d56a4a..7794977 100644
--- a/src/libiu/iu.c
+++ b/src/libiu/iu.c
@@ -36,9 +36,10 @@
 #include <osmocom/gsm/gsm48.h>
 #include <osmocom/gprs/gprs_msgb.h>
 
-#include <osmocom/sigtran/sua.h>
+#include <osmocom/sigtran/osmo_ss7.h>
 #include <osmocom/sigtran/sccp_sap.h>
 #include <osmocom/sigtran/sccp_helpers.h>
+#include <osmocom/sigtran/protocol/m3ua.h>
 
 #include <openbsc/gprs_sgsn.h>
 #include <openbsc/iu.h>
@@ -63,7 +64,7 @@
 };
 
 /* A remote RNC (Radio Network Controller, like BSC but for UMTS) that has
- * called us and is currently reachable at the given osmo_sccp_link. So, when we
+ * called us and is currently reachable at the given osmo_sccp_addr. So, when we
  * know a LAC for a subscriber, we can page it at the RNC matching that LAC or
  * RAC. An HNB-GW typically presents itself as if it were a single RNC, even
  * though it may have several RNCs in hNodeBs connected to it. Those will then
@@ -75,7 +76,7 @@
 	uint16_t rnc_id;
 	uint16_t lac; /* Location Area Code (used for CS and PS) */
 	uint8_t rac; /* Routing Area Code (used for PS only) */
-	struct osmo_sccp_link *link;
+	struct osmo_sccp_addr sccp_addr;
 };
 
 void *talloc_iu_ctx;
@@ -97,6 +98,9 @@
 static LLIST_HEAD(ue_conn_ctx_list);
 static LLIST_HEAD(rnc_list);
 
+static struct osmo_sccp_instance *g_sccp;
+static struct osmo_sccp_user *g_scu;
+
 const struct value_string iu_event_type_names[] = {
 	OSMO_VALUE_STRING(IU_EVENT_RAB_ASSIGN),
 	OSMO_VALUE_STRING(IU_EVENT_SECURITY_MODE_COMPLETE),
@@ -105,38 +109,37 @@
 	{ 0, NULL }
 };
 
-struct ue_conn_ctx *ue_conn_ctx_alloc(struct osmo_sccp_link *link, uint32_t conn_id)
+struct ue_conn_ctx *ue_conn_ctx_alloc(struct osmo_sccp_addr *addr, uint32_t conn_id)
 {
 	struct ue_conn_ctx *ctx = talloc_zero(talloc_iu_ctx, struct ue_conn_ctx);
 
-	ctx->link = link;
+	ctx->sccp_addr = *addr;
 	ctx->conn_id = conn_id;
 	llist_add(&ctx->list, &ue_conn_ctx_list);
 
 	return ctx;
 }
 
-struct ue_conn_ctx *ue_conn_ctx_find(struct osmo_sccp_link *link,
-				     uint32_t conn_id)
+struct ue_conn_ctx *ue_conn_ctx_find(uint32_t conn_id)
 {
 	struct ue_conn_ctx *ctx;
 
 	llist_for_each_entry(ctx, &ue_conn_ctx_list, list) {
-		if (ctx->link == link && ctx->conn_id == conn_id)
+		if (ctx->conn_id == conn_id)
 			return ctx;
 	}
 	return NULL;
 }
 
 static struct iu_rnc *iu_rnc_alloc(uint16_t rnc_id, uint16_t lac, uint8_t rac,
-				   struct osmo_sccp_link *link)
+				   struct osmo_sccp_addr *addr)
 {
 	struct iu_rnc *rnc = talloc_zero(talloc_iu_ctx, struct iu_rnc);
 
 	rnc->rnc_id = rnc_id;
 	rnc->lac = lac;
 	rnc->rac = rac;
-	rnc->link = link;
+	rnc->sccp_addr = *addr;
 	llist_add(&rnc->entry, &rnc_list);
 
 	LOGP(DRANAP, LOGL_NOTICE, "New RNC %d (LAC=%d RAC=%d)\n",
@@ -146,7 +149,7 @@
 }
 
 static struct iu_rnc *iu_rnc_register(uint16_t rnc_id, uint16_t lac,
-				      uint8_t rac, struct osmo_sccp_link *link)
+				      uint8_t rac, struct osmo_sccp_addr *addr)
 {
 	struct iu_rnc *rnc;
 	llist_for_each_entry(rnc, &rnc_list, entry) {
@@ -165,42 +168,16 @@
 		rnc->lac = lac;
 		rnc->rac = rac;
 
-		if (link && rnc->link != link)
-			LOGP(DRANAP, LOGL_NOTICE, "RNC %d on new link"
+		if (addr && memcmp(&rnc->sccp_addr, addr, sizeof(*addr)))
+			LOGP(DRANAP, LOGL_NOTICE, "RNC %d on New SCCP Addr %s"
 			     " (LAC=%d RAC=%d)\n",
-			     rnc->rnc_id, rnc->lac, rnc->rac);
-		rnc->link = link;
+			     rnc->rnc_id, osmo_sccp_addr_dump(addr), rnc->lac, rnc->rac);
+		rnc->sccp_addr = *addr;
 		return rnc;
 	}
 
 	/* Not found, make a new one. */
-	return iu_rnc_alloc(rnc_id, lac, rac, link);
-}
-
-/* Discard/invalidate all ue_conn_ctx and iu_rnc entries that reference the
- * given link, since this link is invalid and about to be deallocated. For
- * each ue_conn_ctx, invoke the iu_event_cb_t with IU_EVENT_LINK_INVALIDATED.
- */
-void iu_link_del(struct osmo_sccp_link *link)
-{
-	struct iu_rnc *rnc, *rnc_next;
-	llist_for_each_entry_safe(rnc, rnc_next, &rnc_list, entry) {
-		if (!rnc->link)
-			continue;
-		if (rnc->link != link)
-			continue;
-		rnc->link = NULL;
-		llist_del(&rnc->entry);
-		talloc_free(rnc);
-	}
-
-	struct ue_conn_ctx *uec, *uec_next;
-	llist_for_each_entry_safe(uec, uec_next, &ue_conn_ctx_list, list) {
-		if (uec->link != link)
-			continue;
-		uec->link = NULL;
-		global_iu_event_cb(uec, IU_EVENT_LINK_INVALIDATED, NULL);
-	}
+	return iu_rnc_alloc(rnc_id, lac, rac, addr);
 }
 
 /***********************************************************************
@@ -219,7 +196,7 @@
 		       OSMO_SCU_PRIM_N_DATA,
 		       PRIM_OP_REQUEST,
 		       msg);
-	return osmo_sua_user_link_down(ue_ctx->link, &prim->oph);
+	return osmo_sccp_user_sap_down(g_scu, &prim->oph);
 }
 
 int iu_rab_deact(struct ue_conn_ctx *ue_ctx, uint8_t rab_id)
@@ -244,7 +221,7 @@
 	osmo_prim_init(&prim->oph, SCCP_SAP_USER,
 			OSMO_SCU_PRIM_N_DATA,
 			PRIM_OP_REQUEST, msg);
-	osmo_sua_user_link_down(uectx->link, &prim->oph);
+	osmo_sccp_user_sap_down(g_scu, &prim->oph);
 
 	return 0;
 }
@@ -254,8 +231,8 @@
 	struct msgb *msg;
 	struct osmo_scu_prim *prim;
 
-	LOGP(DRANAP, LOGL_INFO, "Transmitting RANAP CommonID (SUA link %p conn_id %u)\n",
-	     uectx->link, uectx->conn_id);
+	LOGP(DRANAP, LOGL_INFO, "Transmitting RANAP CommonID (SCCP conn_id %u)\n",
+	     uectx->conn_id);
 
 	msg = ranap_new_msg_common_id(imsi);
 	msg->l2h = msg->data;
@@ -264,7 +241,7 @@
 	osmo_prim_init(&prim->oph, SCCP_SAP_USER,
 			OSMO_SCU_PRIM_N_DATA,
 			PRIM_OP_REQUEST, msg);
-	osmo_sua_user_link_down(uectx->link, &prim->oph);
+	osmo_sccp_user_sap_down(g_scu, &prim->oph);
 	return 0;
 }
 
@@ -325,7 +302,7 @@
 	memcpy(msgb_gmmh(msg), ies->nas_pdu.buf, ies->nas_pdu.size);
 
 	/* Make sure we know the RNC Id and LAC+RAC coming in on this connection. */
-	iu_rnc_register(grnc_id.rnc_id, ra_id.lac, ra_id.rac, ue_conn->link);
+	iu_rnc_register(grnc_id.rnc_id, ra_id.lac, ra_id.rac, &ue_conn->sccp_addr);
 	ue_conn->ra_id = ra_id;
 
 	/* Feed into the MM layer */
@@ -387,8 +364,8 @@
 	struct msgb *msg;
 	struct osmo_scu_prim *prim;
 
-	LOGP(DRANAP, LOGL_INFO, "Transmitting L3 Message as RANAP DT (SUA link %p conn_id %u)\n",
-	     uectx->link, uectx->conn_id);
+	LOGP(DRANAP, LOGL_INFO, "Transmitting L3 Message as RANAP DT (SCCP conn_id %u)\n",
+	     uectx->conn_id);
 
 	msg = ranap_new_msg_dt(sapi, msg_nas->data, msgb_length(msg_nas));
 	msgb_free(msg_nas);
@@ -398,7 +375,7 @@
 	osmo_prim_init(&prim->oph, SCCP_SAP_USER,
 			OSMO_SCU_PRIM_N_DATA,
 			PRIM_OP_REQUEST, msg);
-	osmo_sua_user_link_down(uectx->link, &prim->oph);
+	osmo_sccp_user_sap_down(g_scu, &prim->oph);
 	return 0;
 }
 
@@ -417,6 +394,9 @@
 	if (!cause)
 		cause = &default_cause;
 
+	LOGP(DRANAP, LOGL_INFO, "Transmitting Iu Release (SCCP conn_id %u)\n",
+	     ctx->conn_id);
+
 	msg = ranap_new_msg_iu_rel_cmd(cause);
 	msg->l2h = msg->data;
 	prim = (struct osmo_scu_prim *) msgb_push(msg, sizeof(*prim));
@@ -424,7 +404,7 @@
 	osmo_prim_init(&prim->oph, SCCP_SAP_USER,
 			OSMO_SCU_PRIM_N_DATA,
 			PRIM_OP_REQUEST, msg);
-	return osmo_sua_user_link_down(ctx->link, &prim->oph);
+	return osmo_sccp_user_sap_down(g_scu, &prim->oph);
 }
 
 static int ranap_handle_co_iu_rel_req(struct ue_conn_ctx *ctx, RANAP_Iu_ReleaseRequestIEs_t *ies)
@@ -595,21 +575,28 @@
  * Paging
  ***********************************************************************/
 
-/* Send a paging command down a given SUA link. tmsi and paging_cause are
+struct osmo_sccp_addr local_sccp_addr = {
+	.presence = OSMO_SCCP_ADDR_T_SSN | OSMO_SCCP_ADDR_T_PC,
+	.ri = OSMO_SCCP_RI_SSN_PC,
+	.ssn = OSMO_SCCP_SSN_RANAP,
+	.pc = 1,
+};
+
+/* Send a paging command down a given SCCP User. tmsi and paging_cause are
  * optional and may be passed NULL and 0, respectively, to disable their use.
  * See enum RANAP_PagingCause.
  *
  * If TMSI is given, the IMSI is not sent over the air interface. Nevertheless,
  * the IMSI is still required for resolution in the HNB-GW and/or(?) RNC. */
-static int iu_tx_paging_cmd(struct osmo_sccp_link *link,
+static int iu_tx_paging_cmd(struct osmo_sccp_addr *called_addr,
 			    const char *imsi, const uint32_t *tmsi,
 			    bool is_ps, uint32_t paging_cause)
 {
 	struct msgb *msg;
 	msg = ranap_new_msg_paging_cmd(imsi, tmsi, is_ps? 1 : 0, paging_cause);
 	msg->l2h = msg->data;
-	return osmo_sccp_tx_unitdata_ranap(link, 1, 2, msg->data,
-					   msgb_length(msg));
+	osmo_sccp_tx_unitdata_msg(g_scu, &local_sccp_addr, called_addr, msg);
+	return 0;
 }
 
 static int iu_page(const char *imsi, const uint32_t *tmsi_or_ptimsi,
@@ -634,22 +621,18 @@
 	}
 
 	llist_for_each_entry(rnc, &rnc_list, entry) {
-		if (!rnc->link) {
-			/* Not actually connected, don't count it. */
-			continue;
-		}
 		if (rnc->lac != lac)
 			continue;
 		if (is_ps && rnc->rac != rac)
 			continue;
 
 		/* Found a match! */
-		if (iu_tx_paging_cmd(rnc->link, imsi, tmsi_or_ptimsi, is_ps, 0)
+		if (iu_tx_paging_cmd(&rnc->sccp_addr, imsi, tmsi_or_ptimsi, is_ps, 0)
 		    == 0) {
 			LOGP(DRANAP, LOGL_DEBUG,
-			     "%s: Paged for IMSI %s on RNC %d, on SUA link %p\n",
+			     "%s: Paged for IMSI %s on RNC %d, on SCCP addr %s\n",
 			     is_ps? "IuPS" : "IuCS",
-			     imsi, rnc->rnc_id, rnc->link);
+			     imsi, rnc->rnc_id, osmo_sccp_addr_dump(&rnc->sccp_addr));
 			pagings_sent ++;
 		}
 	}
@@ -692,8 +675,8 @@
  *
  ***********************************************************************/
 
-int tx_unitdata(struct osmo_sccp_link *link);
-int tx_conn_req(struct osmo_sccp_link *link, uint32_t conn_id);
+int tx_unitdata(struct osmo_sccp_user *scu);
+int tx_conn_req(struct osmo_sccp_user *scu, uint32_t conn_id);
 
 struct osmo_prim_hdr *make_conn_req(uint32_t conn_id);
 struct osmo_prim_hdr *make_dt1_req(uint32_t conn_id, const uint8_t *data, unsigned int len);
@@ -711,8 +694,9 @@
 	return &prim->oph;
 }
 
-static int sccp_sap_up(struct osmo_prim_hdr *oph, void *link)
+static int sccp_sap_up(struct osmo_prim_hdr *oph, void *_scu)
 {
+	struct osmo_sccp_user *scu = _scu;
 	struct osmo_scu_prim *prim = (struct osmo_scu_prim *) oph;
 	struct osmo_prim_hdr *resp = NULL;
 	int rc;
@@ -734,10 +718,10 @@
 			     "Received invalid N-CONNECT.ind\n");
 			return 0;
 		}
-		ue = ue_conn_ctx_alloc(link, prim->u.connect.conn_id);
-		/* first ensure the local SUA/SCCP socket is ACTIVE */
+		ue = ue_conn_ctx_alloc(&prim->u.connect.calling_addr, prim->u.connect.conn_id);
+		/* first ensure the local SCCP socket is ACTIVE */
 		resp = make_conn_resp(&prim->u.connect);
-		osmo_sua_user_link_down(link, resp);
+		osmo_sccp_user_sap_down(scu, resp);
 		/* then handle the RANAP payload */
 		rc = ranap_cn_rx_co(cn_ranap_handle_co, ue, msgb_l2(oph->msg), msgb_l2len(oph->msg));
 		break;
@@ -745,7 +729,7 @@
 		/* indication of disconnect */
 		DEBUGP(DRANAP, "N-DISCONNECT.ind(%u)\n",
 		       prim->u.disconnect.conn_id);
-		ue = ue_conn_ctx_find(link, prim->u.disconnect.conn_id);
+		ue = ue_conn_ctx_find(prim->u.disconnect.conn_id);
 		rc = ranap_cn_rx_co(cn_ranap_handle_co, ue, msgb_l2(oph->msg), msgb_l2len(oph->msg));
 		break;
 	case OSMO_PRIM(OSMO_SCU_PRIM_N_DATA, PRIM_OP_INDICATION):
@@ -753,14 +737,14 @@
 		DEBUGP(DRANAP, "N-DATA.ind(%u, %s)\n", prim->u.data.conn_id,
 		       osmo_hexdump(msgb_l2(oph->msg), msgb_l2len(oph->msg)));
 		/* resolve UE context */
-		ue = ue_conn_ctx_find(link, prim->u.data.conn_id);
+		ue = ue_conn_ctx_find(prim->u.data.conn_id);
 		rc = ranap_cn_rx_co(cn_ranap_handle_co, ue, msgb_l2(oph->msg), msgb_l2len(oph->msg));
 		break;
 	case OSMO_PRIM(OSMO_SCU_PRIM_N_UNITDATA, PRIM_OP_INDICATION):
 		/* connection-less data received */
 		DEBUGP(DRANAP, "N-UNITDATA.ind(%s)\n",
 		       osmo_hexdump(msgb_l2(oph->msg), msgb_l2len(oph->msg)));
-		rc = ranap_cn_rx_cl(cn_ranap_handle_cl, link, msgb_l2(oph->msg), msgb_l2len(oph->msg));
+		rc = ranap_cn_rx_cl(cn_ranap_handle_cl, scu, msgb_l2(oph->msg), msgb_l2len(oph->msg));
 		break;
 	default:
 		rc = -1;
@@ -771,17 +755,17 @@
 	return rc;
 }
 
-int iu_init(void *ctx, const char *listen_addr, uint16_t listen_port,
+int iu_init(void *ctx, struct osmo_sccp_instance *sccp,
 	    iu_recv_cb_t iu_recv_cb, iu_event_cb_t iu_event_cb)
 {
-	struct osmo_sccp_user *user;
 	talloc_iu_ctx = talloc_named_const(ctx, 1, "iu");
 	talloc_asn1_ctx = talloc_named_const(talloc_iu_ctx, 1, "asn1");
 
 	global_iu_recv_cb = iu_recv_cb;
 	global_iu_event_cb = iu_event_cb;
-	osmo_sua_set_log_area(DSUA);
-	user = osmo_sua_user_create(talloc_iu_ctx, sccp_sap_up, talloc_iu_ctx);
-	return osmo_sua_server_listen(user, listen_addr, listen_port);
+	g_sccp = sccp;
+	g_scu = osmo_sccp_user_bind(g_sccp, "OsmoMSC-Iu", sccp_sap_up, OSMO_SCCP_SSN_RANAP);
+
+	return 0;
 }
 
diff --git a/src/libiu/iu_vty.c b/src/libiu/iu_vty.c
index 73ad126..3fd3cd1 100644
--- a/src/libiu/iu_vty.c
+++ b/src/libiu/iu_vty.c
@@ -23,6 +23,8 @@
 #include <osmocom/core/logging.h>
 #include <osmocom/vty/command.h>
 #include <osmocom/vty/logging.h>
+#include <osmocom/sigtran/osmo_ss7.h>
+#include <osmocom/sigtran/sccp_sap.h>
 
 #include <openbsc/iu.h>
 
@@ -52,9 +54,10 @@
 	return CMD_SUCCESS;
 }
 
+#define IU_STR "Iu interface protocol options\n"
 DEFUN(cfg_iu_rab_assign_addr_enc, cfg_iu_rab_assign_addr_enc_cmd,
       "iu rab-assign-addr-enc (x213|v4raw)",
-      "Iu interface protocol options\n"
+      IU_STR
       "Choose RAB Assignment's Transport Layer Address encoding\n"
       "ITU-T X.213 compliant address encoding (default)\n"
       "32bit length raw IPv4 address (for ip.access nano3G)\n")
@@ -72,6 +75,24 @@
 	return CMD_SUCCESS;
 }
 
+extern struct osmo_sccp_addr local_sccp_addr;
+
+/* Note from the future: change-id Ib8c4fcdb4766c5e575618b95ce16dce51063206b will move this file to
+ * osmo-iuh, and there, change-id I3bb7fc1cd5261d214c6ba0cccfe95f637e6db087 will drop this vty command
+ * and use the point code defined via libosmo-sccp vty commands instead. */
+DEFUN(cfg_iu_local_addr_pc, cfg_iu_local_addr_pc_cmd,
+	"iu local-address point-code PC",
+	IU_STR "Local SCCP Address\n" "Set local point code\n" "point code\n")
+{
+	local_sccp_addr.presence = OSMO_SCCP_ADDR_T_PC | OSMO_SCCP_ADDR_T_SSN;
+	local_sccp_addr.ri = OSMO_SCCP_RI_SSN_PC;
+	local_sccp_addr.pc = osmo_ss7_pointcode_parse(NULL, argv[0]);
+
+	return CMD_SUCCESS;
+}
+
+/* TODO: GT address configuration, in line with 4.5.1.1.1 of TS 25.410 */
+
 int iu_vty_config_write(struct vty *vty, const char *indent)
 {
 	if (!g_rab_assign_addr_enc) {
@@ -95,6 +116,9 @@
 		return CMD_WARNING;
 	}
 
+	vty_out(vty, "%siu local-address point-code %s%s", indent,
+		osmo_ss7_pointcode_print(NULL, local_sccp_addr.pc), VTY_NEWLINE);
+
 	return CMD_SUCCESS;
 }
 
@@ -105,4 +129,5 @@
 	install_element(CFG_LOG_NODE, &logging_asn_debug_cmd);
 	install_element(CFG_LOG_NODE, &logging_asn_xer_print_cmd);
 	install_element(iu_parent_node, &cfg_iu_rab_assign_addr_enc_cmd);
+	install_element(iu_parent_node, &cfg_iu_local_addr_pc_cmd);
 }
diff --git a/src/libmgcp/mgcp_protocol.c b/src/libmgcp/mgcp_protocol.c
index 96542c5..c8b6e86 100644
--- a/src/libmgcp/mgcp_protocol.c
+++ b/src/libmgcp/mgcp_protocol.c
@@ -66,6 +66,45 @@
 
 static int mgcp_analyze_header(struct mgcp_parse_data *parse, char *data);
 
+/* Display an mgcp message on the log output */
+void display_mgcp_message(unsigned char *message, unsigned int len,
+			  char *preamble)
+{
+	unsigned char line[80];
+	unsigned char *ptr;
+	unsigned int consumed = 0;
+	unsigned int consumed_line = 0;
+	unsigned int line_count = 0;
+
+	if (!log_check_level(DMGCP, LOGL_DEBUG))
+		return;
+
+	while (1) {
+		memset(line, 0, sizeof(line));
+		ptr = line;
+		consumed_line = 0;
+		do {
+			if (*message != '\n' && *message != '\r') {
+				*ptr = *message;
+				ptr++;
+			}
+			message++;
+			consumed++;
+			consumed_line++;
+		} while (*message != '\n' && consumed < len
+			 && consumed_line < sizeof(line));
+
+		if (strlen((const char *)line)) {
+			LOGP(DMGCP, LOGL_DEBUG, "%s: line #%02u: %s\n",
+			     preamble, line_count, line);
+			line_count++;
+		}
+
+		if (consumed >= len)
+			return;
+	}
+}
+
 static int mgcp_check_param(const struct mgcp_endpoint *endp, const char *line)
 {
 	const size_t line_len = strlen(line);
@@ -157,7 +196,8 @@
 	}
 
 	res->l2h = msgb_put(res, len);
-	LOGP(DMGCP, LOGL_DEBUG, "Generated response: code: %d for '%s'\n", code, res->l2h);
+	LOGP(DMGCP, LOGL_DEBUG, "Generated response: code=%d\n", code);
+	display_mgcp_message(res->l2h, msgb_l2len(res), "Generated response");
 
 	/*
 	 * Remember the last transmission per endpoint.
@@ -329,6 +369,8 @@
 	if (mgcp_msg_terminate_nul(msg))
 		return NULL;
 
+	display_mgcp_message(msg->l2h, msgb_l2len(msg), "Received message");
+
         /* attempt to treat it as a response */
         if (sscanf((const char *)&msg->l2h[0], "%3d %*s", &code) == 1) {
 		LOGP(DMGCP, LOGL_DEBUG, "Response: Code: %d\n", code);
diff --git a/src/libmgcp/mgcpgw_client.c b/src/libmgcp/mgcpgw_client.c
index 9f0c84d..1910a9f 100644
--- a/src/libmgcp/mgcpgw_client.c
+++ b/src/libmgcp/mgcpgw_client.c
@@ -35,15 +35,6 @@
 #include <unistd.h>
 #include <string.h>
 
-struct mgcpgw_client {
-	struct mgcpgw_client_conf actual;
-	uint32_t remote_addr;
-	struct osmo_wqueue wq;
-	mgcp_trans_id_t next_trans_id;
-	uint16_t next_endpoint;
-	struct llist_head responses_pending;
-};
-
 void mgcpgw_client_conf_init(struct mgcpgw_client_conf *conf)
 {
 	/* NULL and -1 default to MGCPGW_CLIENT_*_DEFAULT values */
@@ -52,12 +43,68 @@
 		.local_port = -1,
 		.remote_addr = NULL,
 		.remote_port = -1,
+		.first_endpoint = 0,
+		.last_endpoint = 0,
+		.bts_base = 0,
 	};
 }
 
-unsigned int mgcpgw_client_next_endpoint(struct mgcpgw_client *client)
+/* Test if a given endpoint id is currently in use */
+static bool endpoint_in_use(uint16_t id, struct mgcpgw_client *client)
 {
-	return client->next_endpoint ++;
+	struct mgcp_inuse_endpoint *endpoint;
+	llist_for_each_entry(endpoint, &client->inuse_endpoints, entry) {
+		if (endpoint->id == id)
+			return true;
+	}
+
+	return false;
+}
+
+/* Find and seize an unsused endpoint id */
+int mgcpgw_client_next_endpoint(struct mgcpgw_client *client)
+{
+	int i;
+	uint16_t first_endpoint = client->actual.first_endpoint;
+	uint16_t last_endpoint = client->actual.last_endpoint;
+	struct mgcp_inuse_endpoint *endpoint;
+
+	/* Use the maximum permitted range if the VTY
+	 * configuration does not specify a range */
+	if (client->actual.last_endpoint == 0) {
+		first_endpoint = 1;
+		last_endpoint = 65534;
+	}
+
+	/* Test the permitted endpoint range for an endpoint
+	 * number that is not in use. When a suitable endpoint
+	 * number can be found, seize it by adding it to the
+	 * inuse list. */
+	for (i=first_endpoint;i<last_endpoint;i++)
+	{
+		if (endpoint_in_use(i,client) == false) {
+			endpoint = talloc_zero(client, struct mgcp_inuse_endpoint);
+			endpoint->id = i;
+			llist_add_tail(&endpoint->entry, &client->inuse_endpoints);
+			return endpoint->id;
+		}
+	}
+
+	/* All endpoints are busy! */
+	return -EINVAL;
+}
+
+/* Release a seized endpoint id to make it available again for other calls */
+void mgcpgw_client_release_endpoint(uint16_t id, struct mgcpgw_client *client)
+{
+	struct mgcp_inuse_endpoint *endpoint;
+	struct mgcp_inuse_endpoint *endpoint_tmp;
+	llist_for_each_entry_safe(endpoint, endpoint_tmp, &client->inuse_endpoints, entry) {
+		if (endpoint->id == id) {
+			llist_del(&endpoint->entry);
+			talloc_free(endpoint);
+		}
+	}
 }
 
 static void mgcpgw_client_handle_response(struct mgcpgw_client *mgcp,
@@ -257,9 +304,16 @@
 {
 	int ret;
 	static char strbuf[4096];
-	unsigned int l = msg->len < sizeof(strbuf)-1 ? msg->len : sizeof(strbuf)-1;
+	unsigned int l = msg->len < sizeof(strbuf) ? msg->len : sizeof(strbuf);
+	unsigned int i;
+
 	strncpy(strbuf, (const char*)msg->data, l);
-	strbuf[l] = '\0';
+	for (i = 0; i < sizeof(strbuf); i++) {
+		if (strbuf[i] == '\n' || strbuf[i] == '\r') {
+			strbuf[i] = '\0';
+			break;
+		}
+	}
 	DEBUGP(DMGCP, "Tx MGCP msg to MGCP GW: '%s'\n", strbuf);
 
 	LOGP(DMGCP, LOGL_DEBUG, "Sending msg to MGCP GW size: %u\n", msg->len);
@@ -280,9 +334,9 @@
 	mgcp = talloc_zero(ctx, struct mgcpgw_client);
 
 	INIT_LLIST_HEAD(&mgcp->responses_pending);
+	INIT_LLIST_HEAD(&mgcp->inuse_endpoints);
 
 	mgcp->next_trans_id = 1;
-	mgcp->next_endpoint = 1;
 
 	mgcp->actual.local_addr = conf->local_addr ? conf->local_addr :
 		MGCPGW_CLIENT_LOCAL_ADDR_DEFAULT;
@@ -294,6 +348,10 @@
 	mgcp->actual.remote_port = conf->remote_port >= 0 ? (uint16_t)conf->remote_port :
 		MGCPGW_CLIENT_REMOTE_PORT_DEFAULT;
 
+	mgcp->actual.first_endpoint = conf->first_endpoint > 0 ? (uint16_t)conf->first_endpoint : 0;
+	mgcp->actual.last_endpoint = conf->last_endpoint > 0 ? (uint16_t)conf->last_endpoint : 0;
+	mgcp->actual.bts_base = conf->bts_base > 0 ? (uint16_t)conf->bts_base : 4000;
+
 	return mgcp;
 }
 
@@ -547,3 +605,12 @@
 		 rtp_conn_addr,
 		 rtp_port);
 }
+
+struct msgb *mgcp_msg_dlcx(struct mgcpgw_client *mgcp, uint16_t rtp_endpoint,
+			   unsigned int call_id)
+{
+	mgcp_trans_id_t trans_id = mgcpgw_client_next_trans_id(mgcp);
+	return mgcp_msg_from_str(trans_id,
+				 "DLCX %u %x@mgw MGCP 1.0\r\n"
+				 "C: %x\r\n", trans_id, rtp_endpoint, call_id);
+}
diff --git a/src/libmgcp/mgcpgw_client_vty.c b/src/libmgcp/mgcpgw_client_vty.c
index a42ee4e..8068000 100644
--- a/src/libmgcp/mgcpgw_client_vty.c
+++ b/src/libmgcp/mgcpgw_client_vty.c
@@ -79,10 +79,46 @@
 	return CMD_SUCCESS;
 }
 
+DEFUN(cfg_mgcpgw_endpoint_range, cfg_mgcpgw_endpoint_range_cmd,
+      "mgcpgw endpoint-range <1-65534> <1-65534>",
+      MGCPGW_STR "usable range of endpoint identifiers\n"
+      "set first useable endpoint identifier\n"
+      "set the last useable endpoint identifier\n")
+{
+	uint16_t first_endpoint = atoi(argv[0]);
+	uint16_t last_endpoint = atoi(argv[1]);
+
+	if (last_endpoint < first_endpoint) {
+		vty_out(vty, "last endpoint must be greater than first endpoint!%s",
+			VTY_NEWLINE);
+		return CMD_SUCCESS;
+	}
+
+	global_mgcpgw_client_conf->first_endpoint = first_endpoint;
+	global_mgcpgw_client_conf->last_endpoint = last_endpoint;
+	return CMD_SUCCESS;
+}
+
+#define BTS_START_STR "First UDP port allocated for the BTS side\n"
+#define UDP_PORT_STR "UDP Port number\n"
+DEFUN(cfg_mgcp_rtp_bts_base_port,
+      cfg_mgcp_rtp_bts_base_port_cmd,
+      "mgcpgw bts-base <0-65534>",
+      MGCPGW_STR
+      BTS_START_STR
+      UDP_PORT_STR)
+{
+	global_mgcpgw_client_conf->bts_base = atoi(argv[0]);
+	return CMD_SUCCESS;
+}
+
 int mgcpgw_client_config_write(struct vty *vty, const char *indent)
 {
 	const char *addr;
 	int port;
+	uint16_t first_endpoint;
+	uint16_t last_endpoint;
+	uint16_t bts_base;
 
 	addr = global_mgcpgw_client_conf->local_addr;
 	if (addr)
@@ -102,6 +138,19 @@
 		vty_out(vty, "%smgcpgw remote-port %u%s", indent,
 			(uint16_t)port, VTY_NEWLINE);
 
+	first_endpoint = global_mgcpgw_client_conf->first_endpoint;
+	last_endpoint = global_mgcpgw_client_conf->last_endpoint;
+	if (last_endpoint != 0) {
+		vty_out(vty, "%smgcpgw endpoint-range %u %u%s", indent,
+			first_endpoint, last_endpoint, VTY_NEWLINE);
+	}
+
+	bts_base = global_mgcpgw_client_conf->bts_base;
+	if (bts_base) {
+		vty_out(vty, "%smgcpgw bts-base %u%s", indent,
+			bts_base, VTY_NEWLINE);
+	}
+
 	return CMD_SUCCESS;
 }
 
@@ -113,4 +162,6 @@
 	install_element(node, &cfg_mgcpgw_local_port_cmd);
 	install_element(node, &cfg_mgcpgw_remote_ip_cmd);
 	install_element(node, &cfg_mgcpgw_remote_port_cmd);
+	install_element(node, &cfg_mgcpgw_endpoint_range_cmd);
+	install_element(node, &cfg_mgcp_rtp_bts_base_port_cmd);
 }
diff --git a/src/libmsc/Makefile.am b/src/libmsc/Makefile.am
index 4726bbe..9f246b3 100644
--- a/src/libmsc/Makefile.am
+++ b/src/libmsc/Makefile.am
@@ -13,6 +13,7 @@
 	$(LIBCRYPTO_CFLAGS) \
 	$(LIBSMPP34_CFLAGS) \
 	$(LIBASN1C_CFLAGS) \
+	$(LIBOSMOSIGTRAN_CFLAGS) \
 	$(NULL)
 
 noinst_HEADERS = \
@@ -25,6 +26,7 @@
 
 libmsc_a_SOURCES = \
 	a_iface.c \
+	a_iface_bssap.c \
 	auth.c \
 	msc_vty.c \
 	db.c \
diff --git a/src/libmsc/a_iface.c b/src/libmsc/a_iface.c
index caf9d4b..93e8ab5 100644
--- a/src/libmsc/a_iface.c
+++ b/src/libmsc/a_iface.c
@@ -1,9 +1,8 @@
-/* A-interface implementation, from MSC to BSC */
-
-/* (C) 2016 by sysmocom s.m.f.c GmbH <info@sysmocom.de>
- *
+/* (C) 2017 by sysmocom s.f.m.c. GmbH
  * All Rights Reserved
  *
+ * Author: Philipp Maier
+ *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU Affero General Public License as published by
  * the Free Software Foundation; either version 3 of the License, or
@@ -19,35 +18,574 @@
  *
  */
 
+#include <osmocom/core/utils.h>
 #include <osmocom/core/msgb.h>
 #include <osmocom/core/logging.h>
-
+#include <osmocom/sigtran/sccp_helpers.h>
+#include <osmocom/sigtran/sccp_sap.h>
+#include <osmocom/sigtran/osmo_ss7.h>
+#include <osmocom/sigtran/protocol/m3ua.h>
+#include <osmocom/gsm/gsm0808.h>
+#include <osmocom/gsm/protocol/gsm_08_08.h>
+#include <osmocom/gsm/protocol/gsm_04_08.h>
+#include <osmocom/gsm/gsm0808_utils.h>
 #include <openbsc/debug.h>
-
-#include <openbsc/gsm_data.h>
 #include <openbsc/msc_ifaces.h>
-#include <openbsc/debug.h>
+#include <openbsc/a_iface.h>
+#include <openbsc/a_iface_bssap.h>
+#include <openbsc/transaction.h>
+#include <openbsc/mgcpgw_client.h>
+#include <osmocom/core/byteswap.h>
+#include <osmocom/sccp/sccp_types.h>
+#include <openbsc/a_reset.h>
+#include <openbsc/osmo_msc.h>
 
-int a_tx(struct msgb *msg)
+/* A pointer to the GSM network we work with. By the current paradigm,
+ * there can only be one gsm_network per MSC. The pointer is set once
+ * when calling a_init() */
+static struct gsm_network *gsm_network = NULL;
+
+/* A struct to track currently active connections. We need that information
+ * to handle failure sitautions. In case of a problem, we must know which
+ * connections are currently open and which BSC is responsible. We also need
+ * the data to perform our connection checks (a_reset). All other logic will
+ * look at the connection ids and addresses that are supplied by the
+ * primitives */
+struct bsc_conn {
+	struct llist_head list;
+	uint32_t conn_id;			/* Connection identifier */
+};
+
+/* Internal list with connections we currently maintain. This
+ * list is of type struct bsc_conn (see above) */
+static LLIST_HEAD(active_connections);
+
+/* Record info of a new active connection in the active connection list */
+static void record_bsc_con(const void *ctx, uint32_t conn_id)
 {
-	LOGP(DMSC, LOGL_ERROR, "message to be sent to BSC, but A-interface"
-	     " not implemented.\n%s\n", osmo_hexdump(msg->data, msg->len));
-	return -1;
+	struct bsc_conn *conn;
+
+	conn = talloc_zero(ctx, struct bsc_conn);
+	OSMO_ASSERT(conn);
+
+	conn->conn_id = conn_id;
+
+	llist_add_tail(&conn->list, &active_connections);
 }
 
-int a_page(const char *imsi, uint32_t tmsi, uint16_t lac)
+/* Delete info of a closed connection from the active connection list */
+void a_delete_bsc_con(uint32_t conn_id)
 {
-	LOGP(DMSC, LOGL_ERROR, "Paging to be sent to BSC, but A-interface"
-	     " not implemented: IMSI %s TMSI 0x%08x LAC %u\n",
-	     imsi, tmsi, lac);
-	return -1;
+	struct bsc_conn *conn;
+	struct bsc_conn *conn_temp;
+
+	LOGP(DMSC, LOGL_DEBUG,
+	     "Removing connection from active sccp-connection list (conn_id=%i)\n",
+	     conn_id);
+
+	llist_for_each_entry_safe(conn, conn_temp, &active_connections, list) {
+		if (conn->conn_id == conn_id) {
+			llist_del(&conn->list);
+			talloc_free(conn);
+		}
+	}
 }
 
-int msc_gsm0808_tx_cipher_mode(struct gsm_subscriber_connection *conn, int cipher,
-			       const uint8_t *key, int len, int include_imeisv)
+/* Check if a specified connection id has an active SCCP connection */
+static bool check_connection_active(uint32_t conn_id)
+{
+	struct bsc_conn *conn;
+
+	/* Find the address for the current connection id */
+	llist_for_each_entry(conn, &active_connections, list) {
+		if (conn->conn_id == conn_id) {
+			return true;
+		}
+	}
+
+	return false;
+}
+
+/* Get the reset context for a specifiec calling (BSC) address */
+static struct a_reset_ctx *get_reset_ctx_by_sccp_addr(const struct osmo_sccp_addr *addr)
+{
+	struct bsc_context *bsc_ctx;
+	struct osmo_ss7_instance *ss7;
+
+	if (!addr)
+		return NULL;
+
+	llist_for_each_entry(bsc_ctx, &gsm_network->a.bscs, list) {
+		if (memcmp(&bsc_ctx->bsc_addr, addr, sizeof(*addr)) == 0)
+			return bsc_ctx->reset;
+	}
+
+	ss7 = osmo_ss7_instance_find(gsm_network->a.cs7_instance);
+	OSMO_ASSERT(ss7);
+	LOGP(DMSC, LOGL_ERROR, "The calling BSC (%s) is unknown to this MSC ...\n",
+	     osmo_sccp_addr_name(ss7, addr));
+	return NULL;
+}
+
+/* Send DTAP message via A-interface */
+int a_iface_tx_dtap(struct msgb *msg)
+{
+	struct gsm_subscriber_connection *conn;
+	struct msgb *msg_resp;
+
+	/* FIXME: Set this to some meaninful value! */
+	uint8_t link_id = 0x00;
+	OSMO_ASSERT(msg);
+	conn = (struct gsm_subscriber_connection *)msg->dst;
+	OSMO_ASSERT(conn);
+	OSMO_ASSERT(conn->a.scu);
+
+	LOGP(DMSC, LOGL_DEBUG, "Passing DTAP message from MSC to BSC (conn_id=%i)\n", conn->a.conn_id);
+
+	msg->l3h = msg->data;
+	msg_resp = gsm0808_create_dtap(msg, link_id);
+	if (!msg_resp) {
+		LOGP(DMSC, LOGL_ERROR, "Unable to generate BSSMAP DTAP message!\n");
+		return -EINVAL;
+	} else
+		LOGP(DMSC, LOGL_DEBUG, "Massage will be sent as BSSMAP DTAP message!\n");
+
+	LOGP(DMSC, LOGL_DEBUG, "N-DATA.req(%u, %s)\n", conn->a.conn_id, osmo_hexdump(msg_resp->data, msg_resp->len));
+	return osmo_sccp_tx_data_msg(conn->a.scu, conn->a.conn_id, msg_resp);
+}
+
+/* Send Cipher mode command via A-interface */
+int a_iface_tx_cipher_mode(const struct gsm_subscriber_connection *conn,
+			   int cipher, const const uint8_t *key, int len, int include_imeisv)
 {
 	/* TODO generalize for A- and Iu interfaces, don't name after 08.08 */
-	LOGP(DMSC, LOGL_ERROR, "gsm0808_cipher_mode(): message to be sent to"
-	     " BSC, but A interface not yet implemented.\n");
-	return -1;
+	struct msgb *msg_resp;
+	struct gsm0808_encrypt_info ei;
+
+	OSMO_ASSERT(conn);
+
+	LOGP(DMSC, LOGL_DEBUG, "Passing Cipher mode command message from MSC to BSC (conn_id=%i)\n", conn->a.conn_id);
+	uint8_t crm = 0x01;
+	uint8_t *crm_ptr = NULL;
+
+	/* Setup encryption information */
+	if (len > ENCRY_INFO_KEY_MAXLEN || !key) {
+		LOGP(DMSC, LOGL_ERROR,
+		     "Cipher mode command message could not be generated due to invalid key! (conn_id=%i)\n",
+		     conn->a.conn_id);
+		return -EINVAL;
+	} else {
+		memcpy(&ei.key, key, len);
+		ei.key_len = len;
+	}
+
+	if (include_imeisv)
+		crm_ptr = &crm;
+
+	ei.perm_algo[0] = (uint8_t) (1 << cipher);
+	ei.perm_algo_len = 1;
+
+	msg_resp = gsm0808_create_cipher(&ei, crm_ptr);
+	LOGP(DMSC, LOGL_DEBUG, "N-DATA.req(%u, %s)\n", conn->a.conn_id, osmo_hexdump(msg_resp->data, msg_resp->len));
+
+	return osmo_sccp_tx_data_msg(conn->a.scu, conn->a.conn_id, msg_resp);
+}
+
+/* Page a subscriber via A-interface */
+int a_iface_tx_paging(const char *imsi, uint32_t tmsi, uint16_t lac)
+{
+	struct bsc_context *bsc_ctx;
+	struct gsm0808_cell_id_list cil;
+	struct msgb *msg;
+	int page_count = 0;
+	struct osmo_ss7_instance *ss7;
+
+	OSMO_ASSERT(imsi);
+
+	cil.id_discr = CELL_IDENT_LAC;
+	cil.id_list_lac[0] = lac;
+	cil.id_list_len = 1;
+
+	ss7 = osmo_ss7_instance_find(gsm_network->a.cs7_instance);
+	OSMO_ASSERT(ss7);
+
+	/* Deliver paging request to all known BSCs */
+	llist_for_each_entry(bsc_ctx, &gsm_network->a.bscs, list) {
+		if (a_reset_conn_ready(bsc_ctx->reset)) {
+			LOGP(DMSC, LOGL_DEBUG,
+			     "Passing paging message from MSC %s to BSC %s (imsi=%s, tmsi=0x%08x, lac=%u)\n",
+			     osmo_sccp_addr_name(ss7, &bsc_ctx->msc_addr),
+			     osmo_sccp_addr_name(ss7, &bsc_ctx->bsc_addr), imsi, tmsi, lac);
+			msg = gsm0808_create_paging(imsi, &tmsi, &cil, NULL);
+			osmo_sccp_tx_unitdata_msg(bsc_ctx->sccp_user,
+						  &bsc_ctx->msc_addr, &bsc_ctx->bsc_addr, msg);
+			page_count++;
+		} else {
+			LOGP(DMSC, LOGL_DEBUG,
+			     "Connection down, dropping paging from MSC %s to BSC %s (imsi=%s, tmsi=0x%08x, lac=%u)\n",
+			     osmo_sccp_addr_name(ss7, &bsc_ctx->msc_addr),
+			     osmo_sccp_addr_name(ss7, &bsc_ctx->bsc_addr), imsi, tmsi, lac);
+		}
+	}
+
+	if (page_count <= 0)
+		LOGP(DMSC, LOGL_ERROR, "Could not deliver paging because none of the associated BSCs is available!\n");
+
+	return page_count;
+}
+
+/* Convert speech version field */
+static uint8_t convert_Abis_sv_to_A_sv(int speech_ver)
+{
+	/* The speech versions that are transmitted in the Bearer capability
+	 * information element, that is transmitted on the Abis interfece
+	 * use a different encoding than the permitted speech version
+	 * identifier, that is signalled in the channel type element on the A
+	 * interface. (See also 3GPP TS 48.008, 3.2.2.1 and 3GPP TS 24.008,
+	 * 10.5.103 */
+
+	switch (speech_ver) {
+	case GSM48_BCAP_SV_FR:
+		return GSM0808_PERM_FR1;
+		break;
+	case GSM48_BCAP_SV_HR:
+		return GSM0808_PERM_HR1;
+		break;
+	case GSM48_BCAP_SV_EFR:
+		return GSM0808_PERM_FR2;
+		break;
+	case GSM48_BCAP_SV_AMR_F:
+		return GSM0808_PERM_FR3;
+		break;
+	case GSM48_BCAP_SV_AMR_H:
+		return GSM0808_PERM_HR3;
+		break;
+	case GSM48_BCAP_SV_AMR_OFW:
+		return GSM0808_PERM_FR4;
+		break;
+	case GSM48_BCAP_SV_AMR_OHW:
+		return GSM0808_PERM_HR4;
+		break;
+	case GSM48_BCAP_SV_AMR_FW:
+		return GSM0808_PERM_FR5;
+		break;
+	case GSM48_BCAP_SV_AMR_OH:
+		return GSM0808_PERM_HR6;
+		break;
+	}
+
+	/* If nothing matches, tag the result as invalid */
+	LOGP(DMSC, LOGL_ERROR, "Invalid permitted speech version / rate detected, discarding.\n");
+	return 0xFF;
+}
+
+/* Convert speech preference field */
+static uint8_t convert_Abis_prev_to_A_pref(int radio)
+{
+	/* The Radio channel requirement field that is transmitted in the
+	 * Bearer capability information element, that is transmitted on the
+	 * Abis interfece uses a different encoding than the Channel rate and
+	 * type field that is signalled in the channel type element on the A
+	 * interface. (See also 3GPP TS 48.008, 3.2.2.1 and 3GPP TS 24.008,
+	 * 10.5.102 */
+
+	switch (radio) {
+	case GSM48_BCAP_RRQ_FR_ONLY:
+		return GSM0808_SPEECH_FULL_BM;
+	case GSM48_BCAP_RRQ_DUAL_FR:
+		return GSM0808_SPEECH_FULL_PREF;
+	case GSM48_BCAP_RRQ_DUAL_HR:
+		return GSM0808_SPEECH_HALF_PREF;
+	}
+
+	LOGP(DMSC, LOGL_ERROR, "Invalid speech version / rate combination preference, defaulting to full rate.\n");
+	return GSM0808_SPEECH_FULL_BM;
+}
+
+/* Assemble the channel type field */
+static int enc_channel_type(struct gsm0808_channel_type *ct, const struct gsm_mncc_bearer_cap *bc)
+{
+	unsigned int i;
+	uint8_t sv;
+	unsigned int count = 0;
+	bool only_gsm_hr = true;
+
+	OSMO_ASSERT(ct);
+	OSMO_ASSERT(bc);
+
+	ct->ch_indctr = GSM0808_CHAN_SPEECH;
+
+	for (i = 0; i < ARRAY_SIZE(bc->speech_ver); i++) {
+		if (bc->speech_ver[i] == -1)
+			break;
+		sv = convert_Abis_sv_to_A_sv(bc->speech_ver[i]);
+		if (sv != 0xFF) {
+			/* Detect if something else than
+			 * GSM HR V1 is supported */
+			if (sv == GSM0808_PERM_HR2 ||
+			    sv == GSM0808_PERM_HR3 || sv == GSM0808_PERM_HR4 || sv == GSM0808_PERM_HR6)
+				only_gsm_hr = false;
+
+			ct->perm_spch[count] = sv;
+			count++;
+		}
+	}
+	ct->perm_spch_len = count;
+
+	if (only_gsm_hr)
+		/* Note: We must avoid the usage of GSM HR1 as this
+		 * codec only offers very poor audio quality. If the
+		 * MS only supports GSM HR1 (and full rate), and has
+		 * a preference for half rate. Then we will ignore the
+		 * preference and assume a preference for full rate. */
+		ct->ch_rate_type = GSM0808_SPEECH_FULL_BM;
+	else
+		ct->ch_rate_type = convert_Abis_prev_to_A_pref(bc->radio);
+
+	if (count)
+		return 0;
+	else
+		return -EINVAL;
+}
+
+/* Assemble the speech codec field */
+static int enc_speech_codec_list(struct gsm0808_speech_codec_list *scl, const struct gsm0808_channel_type *ct)
+{
+	unsigned int i;
+	int rc;
+
+	memset(scl, 0, sizeof(*scl));
+	for (i = 0; i < ct->perm_spch_len; i++) {
+		rc = gsm0808_speech_codec_from_chan_type(&scl->codec[i], ct->perm_spch[i]);
+		if (rc != 0)
+			return -EINVAL;
+	}
+	scl->len = i;
+
+	return 0;
+}
+
+/* Send assignment request via A-interface */
+int a_iface_tx_assignment(const struct gsm_trans *trans)
+{
+	struct gsm_subscriber_connection *conn;
+	struct gsm0808_channel_type ct;
+	struct gsm0808_speech_codec_list scl;
+	uint32_t *ci_ptr = NULL;
+	struct msgb *msg;
+	struct sockaddr_storage rtp_addr;
+	struct sockaddr_in rtp_addr_in;
+	int rc;
+
+	OSMO_ASSERT(trans);
+	conn = trans->conn;
+	OSMO_ASSERT(conn);
+
+	LOGP(DMSC, LOGL_ERROR, "Sending assignment command to BSC (conn_id %u)\n", conn->a.conn_id);
+
+	/* Channel type */
+	rc = enc_channel_type(&ct, &trans->bearer_cap);
+	if (rc < 0) {
+		LOGP(DMSC, LOGL_ERROR, "Faild to generate channel type -- assignment not sent!\n");
+		return -EINVAL;
+	}
+
+	/* Speech codec list */
+	rc = enc_speech_codec_list(&scl, &ct);
+	if (rc < 0) {
+		LOGP(DMSC, LOGL_ERROR, "Faild to generate Speech codec list -- assignment not sent!\n");
+		return -EINVAL;
+	}
+
+	/* Package RTP-Address data */
+	memset(&rtp_addr_in, 0, sizeof(rtp_addr_in));
+	rtp_addr_in.sin_family = AF_INET;
+	rtp_addr_in.sin_port = osmo_htons(conn->rtp.port_subscr);
+	rtp_addr_in.sin_addr.s_addr = osmo_htonl(mgcpgw_client_remote_addr_n(gsm_network->mgcpgw.client));
+
+	memset(&rtp_addr, 0, sizeof(rtp_addr));
+	memcpy(&rtp_addr, &rtp_addr_in, sizeof(rtp_addr_in));
+
+	msg = gsm0808_create_ass(&ct, NULL, &rtp_addr, &scl, ci_ptr);
+
+	LOGP(DMSC, LOGL_DEBUG, "N-DATA.req(%u, %s)\n", conn->a.conn_id, osmo_hexdump(msg->data, msg->len));
+	return osmo_sccp_tx_data_msg(conn->a.scu, conn->a.conn_id, msg);
+}
+
+/* Send clear command via A-interface */
+int a_iface_tx_clear_cmd(struct gsm_subscriber_connection *conn)
+{
+	struct msgb *msg;
+
+	LOGP(DMSC, LOGL_NOTICE, "Sending clear command to BSC (conn_id=%u)\n", conn->a.conn_id);
+
+	msg = gsm0808_create_clear_command(GSM0808_CAUSE_CALL_CONTROL);
+	return osmo_sccp_tx_data_msg(conn->a.scu, conn->a.conn_id, msg);
+}
+
+/* Callback function: Close all open connections */
+static void a_reset_cb(const void *priv)
+{
+	struct msgb *msg;
+	struct bsc_context *bsc_ctx = (struct bsc_context*) priv;
+	struct osmo_ss7_instance *ss7;
+
+	/* Skip if the A interface is not properly initalized yet */
+	if (!gsm_network)
+		return;
+
+	/* Clear all now orphaned subscriber connections */
+	a_clear_all(bsc_ctx->sccp_user, &bsc_ctx->bsc_addr);
+
+	/* Send reset to the remote BSC */
+	ss7 = osmo_ss7_instance_find(gsm_network->a.cs7_instance);
+	OSMO_ASSERT(ss7);
+	LOGP(DMSC, LOGL_NOTICE, "Sending RESET to BSC %s\n", osmo_sccp_addr_name(ss7, &bsc_ctx->bsc_addr));
+	msg = gsm0808_create_reset();
+	osmo_sccp_tx_unitdata_msg(bsc_ctx->sccp_user, &bsc_ctx->msc_addr,
+				  &bsc_ctx->bsc_addr, msg);
+}
+
+/* Add a new BSC connection to our internal list with known BSCs */
+static void add_bsc(const struct osmo_sccp_addr *msc_addr, const struct osmo_sccp_addr *bsc_addr,
+		    struct osmo_sccp_user *scu)
+{
+	struct bsc_context *bsc_ctx;
+	struct osmo_ss7_instance *ss7;
+
+	OSMO_ASSERT(bsc_addr);
+	OSMO_ASSERT(msc_addr);
+	OSMO_ASSERT(scu);
+
+	/* Check if we already know this BSC, if yes, skip adding it. */
+	if (get_reset_ctx_by_sccp_addr(bsc_addr))
+		return;
+
+	ss7 = osmo_ss7_instance_find(gsm_network->a.cs7_instance);
+	OSMO_ASSERT(ss7);
+	LOGP(DMSC, LOGL_NOTICE, "Adding new BSC connection for BSC %s...\n", osmo_sccp_addr_name(ss7, bsc_addr));
+
+	/* Generate and fill up a new bsc context */
+	bsc_ctx = talloc_zero(gsm_network, struct bsc_context);
+	OSMO_ASSERT(bsc_ctx);
+	memcpy(&bsc_ctx->bsc_addr, bsc_addr, sizeof(*bsc_addr));
+	memcpy(&bsc_ctx->msc_addr, msc_addr, sizeof(*msc_addr));
+	bsc_ctx->sccp_user = scu;
+	llist_add_tail(&bsc_ctx->list, &gsm_network->a.bscs);
+
+	/* Start reset procedure to make the new connection active */
+	bsc_ctx->reset = a_reset_alloc(bsc_ctx, osmo_sccp_addr_name(ss7, bsc_addr), a_reset_cb, bsc_ctx);
+}
+
+/* Callback function, called by the SSCP stack when data arrives */
+static int sccp_sap_up(struct osmo_prim_hdr *oph, void *_scu)
+{
+	struct osmo_sccp_user *scu = _scu;
+	struct osmo_scu_prim *scu_prim = (struct osmo_scu_prim *)oph;
+	int rc = 0;
+	struct a_conn_info a_conn_info;
+	memset(&a_conn_info, 0, sizeof(a_conn_info));
+	a_conn_info.network = gsm_network;
+	a_conn_info.reset = NULL;
+
+	switch (OSMO_PRIM_HDR(&scu_prim->oph)) {
+	case OSMO_PRIM(OSMO_SCU_PRIM_N_CONNECT, PRIM_OP_INDICATION):
+		/* Handle inbound connection indication */
+		add_bsc(&scu_prim->u.connect.called_addr, &scu_prim->u.connect.calling_addr, scu);
+		a_conn_info.conn_id = scu_prim->u.connect.conn_id;
+		a_conn_info.msc_addr = &scu_prim->u.connect.called_addr;
+		a_conn_info.bsc_addr = &scu_prim->u.connect.calling_addr;
+		a_conn_info.reset = get_reset_ctx_by_sccp_addr(&scu_prim->u.unitdata.calling_addr);
+
+		if (a_reset_conn_ready(a_conn_info.reset) == false) {
+			rc = osmo_sccp_tx_disconn(scu, a_conn_info.conn_id, a_conn_info.msc_addr,
+						  SCCP_RETURN_CAUSE_UNQUALIFIED);
+			break;
+		}
+
+		osmo_sccp_tx_conn_resp(scu, scu_prim->u.connect.conn_id, &scu_prim->u.connect.called_addr, NULL, 0);
+		if (msgb_l2len(oph->msg) > 0) {
+			LOGP(DMSC, LOGL_DEBUG, "N-CONNECT.ind(%u, %s)\n",
+			     scu_prim->u.connect.conn_id, osmo_hexdump(msgb_l2(oph->msg), msgb_l2len(oph->msg)));
+			rc = sccp_rx_dt(scu, &a_conn_info, oph->msg);
+		} else
+			LOGP(DMSC, LOGL_DEBUG, "N-CONNECT.ind(%u)\n", scu_prim->u.connect.conn_id);
+
+		record_bsc_con(scu, scu_prim->u.connect.conn_id);
+		break;
+
+	case OSMO_PRIM(OSMO_SCU_PRIM_N_DATA, PRIM_OP_INDICATION):
+		/* Handle incoming connection oriented data */
+		a_conn_info.conn_id = scu_prim->u.data.conn_id;
+		LOGP(DMSC, LOGL_DEBUG, "N-DATA.ind(%u, %s)\n",
+		     scu_prim->u.data.conn_id, osmo_hexdump(msgb_l2(oph->msg), msgb_l2len(oph->msg)));
+		sccp_rx_dt(scu, &a_conn_info, oph->msg);
+		break;
+
+	case OSMO_PRIM(OSMO_SCU_PRIM_N_UNITDATA, PRIM_OP_INDICATION):
+		/* Handle inbound UNITDATA */
+		add_bsc(&scu_prim->u.unitdata.called_addr, &scu_prim->u.unitdata.calling_addr, scu);
+		a_conn_info.msc_addr = &scu_prim->u.unitdata.called_addr;
+		a_conn_info.bsc_addr = &scu_prim->u.unitdata.calling_addr;
+		a_conn_info.reset = get_reset_ctx_by_sccp_addr(&scu_prim->u.unitdata.calling_addr);
+		DEBUGP(DMSC, "N-UNITDATA.ind(%s)\n", osmo_hexdump(msgb_l2(oph->msg), msgb_l2len(oph->msg)));
+		sccp_rx_udt(scu, &a_conn_info, oph->msg);
+		break;
+
+	default:
+		LOGP(DMSC, LOGL_ERROR, "Unhandled SIGTRAN primitive: %u:%u\n", oph->primitive, oph->operation);
+		break;
+	}
+
+	return rc;
+}
+
+/* Clear all subscriber connections on a specified BSC */
+void a_clear_all(struct osmo_sccp_user *scu, const struct osmo_sccp_addr *bsc_addr)
+{
+	struct gsm_subscriber_connection *conn;
+	struct gsm_subscriber_connection *conn_temp;
+	struct gsm_network *network = gsm_network;
+
+	OSMO_ASSERT(scu);
+	OSMO_ASSERT(bsc_addr);
+
+	llist_for_each_entry_safe(conn, conn_temp, &network->subscr_conns, entry) {
+		/* Clear only A connections and connections that actually
+		 * belong to the specified BSC */
+		if (conn->via_ran == RAN_GERAN_A && memcmp(bsc_addr, &conn->a.bsc_addr, sizeof(conn->a.bsc_addr)) == 0) {
+			LOGP(DMSC, LOGL_NOTICE, "Dropping orphaned subscriber connection (conn_id %i)\n",
+			     conn->a.conn_id);
+			msc_clear_request(conn, GSM48_CC_CAUSE_SWITCH_CONG);
+
+			/* If there is still an SCCP connection active, remove it now */
+			if (check_connection_active(conn->a.conn_id)) {
+				osmo_sccp_tx_disconn(scu, conn->a.conn_id, bsc_addr,
+						     SCCP_RELEASE_CAUSE_END_USER_ORIGINATED);
+				a_delete_bsc_con(conn->a.conn_id);
+			}
+		}
+	}
+}
+
+/* Initalize A interface connection between to MSC and BSC */
+int a_init(struct osmo_sccp_instance *sccp, struct gsm_network *network)
+{
+	OSMO_ASSERT(sccp);
+	OSMO_ASSERT(network);
+
+	/* FIXME: Remove hardcoded parameters, use parameters in parameter list */
+	LOGP(DMSC, LOGL_NOTICE, "Initalizing SCCP connection to stp...\n");
+
+	/* Set GSM network variable, there can only be
+	 * one network by design */
+	if (gsm_network != NULL) {
+		OSMO_ASSERT(gsm_network == network);
+	} else
+		gsm_network = network;
+
+	/* SCCP Protocol stack */
+	osmo_sccp_user_bind(sccp, "OsmoMSC-A", sccp_sap_up, SCCP_SSN_BSSAP);
+
+	return 0;
 }
diff --git a/src/libmsc/a_iface_bssap.c b/src/libmsc/a_iface_bssap.c
new file mode 100644
index 0000000..561ccde
--- /dev/null
+++ b/src/libmsc/a_iface_bssap.c
@@ -0,0 +1,717 @@
+/* (C) 2017 by Sysmocom s.f.m.c. GmbH
+ * All Rights Reserved
+ *
+ * Author: Philipp Maier
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include <osmocom/core/utils.h>
+#include <osmocom/core/msgb.h>
+#include <osmocom/core/logging.h>
+#include <osmocom/sigtran/sccp_helpers.h>
+#include <osmocom/sccp/sccp_types.h>
+#include <osmocom/gsm/gsm0808.h>
+#include <osmocom/gsm/gsm0808_utils.h>
+#include <openbsc/debug.h>
+#include <openbsc/gsm_data.h>
+#include <openbsc/a_iface_bssap.h>
+#include <openbsc/a_iface.h>
+#include <openbsc/iu.h>
+#include <openbsc/osmo_msc.h>
+#include <osmocom/core/byteswap.h>
+#include <openbsc/a_reset.h>
+
+#define IP_V4_ADDR_LEN 4
+
+/*
+ * Helper functions to lookup and allocate subscribers
+ */
+
+/* Allocate a new subscriber connection */
+static struct gsm_subscriber_connection *subscr_conn_allocate_a(const struct a_conn_info *a_conn_info,
+								struct gsm_network *network,
+								uint16_t lac, struct osmo_sccp_user *scu, int conn_id)
+{
+	struct gsm_subscriber_connection *conn;
+
+	LOGP(DMSC, LOGL_NOTICE, "Allocating A-Interface subscriber conn: lac %i, conn_id %i\n", lac, conn_id);
+
+	conn = talloc_zero(network, struct gsm_subscriber_connection);
+	if (!conn)
+		return NULL;
+
+	conn->network = network;
+	conn->via_ran = RAN_GERAN_A;
+	conn->lac = lac;
+
+	conn->a.conn_id = conn_id;
+	conn->a.scu = scu;
+
+	/* Also backup the calling address of the BSC, this allows us to
+	 * identify later which BSC is responsible for this subscriber connection */
+	memcpy(&conn->a.bsc_addr, a_conn_info->bsc_addr, sizeof(conn->a.bsc_addr));
+
+	llist_add_tail(&conn->entry, &network->subscr_conns);
+	LOGP(DMSC, LOGL_NOTICE, "A-Interface subscriber connection successfully allocated!\n");
+	return conn;
+}
+
+/* Return an existing A subscriber connection record for the given
+ * connection IDs, or return NULL if not found. */
+static struct gsm_subscriber_connection *subscr_conn_lookup_a(const struct gsm_network *network, int conn_id)
+{
+	struct gsm_subscriber_connection *conn;
+
+	OSMO_ASSERT(network);
+
+	DEBUGP(DMSC, "Looking for A subscriber: conn_id %i\n", conn_id);
+
+	/* FIXME: log_subscribers() is defined in iucs.c as static inline, if
+	 * maybe this function should be public to reach it from here? */
+	/* log_subscribers(network); */
+
+	llist_for_each_entry(conn, &network->subscr_conns, entry) {
+		if (conn->via_ran == RAN_GERAN_A && conn->a.conn_id == conn_id) {
+			DEBUGP(DIUCS, "Found A subscriber for conn_id %i\n", conn_id);
+			return conn;
+		}
+	}
+	DEBUGP(DMSC, "No A subscriber found for conn_id %i\n", conn_id);
+	return NULL;
+}
+
+/*
+ * BSSMAP handling for UNITDATA
+ */
+
+/* Endpoint to handle BSSMAP reset */
+static void bssmap_rx_reset(struct osmo_sccp_user *scu, const struct a_conn_info *a_conn_info, struct msgb *msg)
+{
+	struct gsm_network *network = a_conn_info->network;
+	struct osmo_ss7_instance *ss7;
+
+	ss7 = osmo_ss7_instance_find(network->a.cs7_instance);
+	OSMO_ASSERT(ss7);
+
+	LOGP(DMSC, LOGL_NOTICE, "Rx RESET from BSC %s, sending RESET ACK\n",
+	     osmo_sccp_addr_name(ss7, a_conn_info->bsc_addr));
+	osmo_sccp_tx_unitdata_msg(scu, a_conn_info->msc_addr, a_conn_info->bsc_addr, gsm0808_create_reset_ack());
+
+	/* Make sure all orphand subscriber connections will be cleard */
+	a_clear_all(scu, a_conn_info->bsc_addr);
+
+	msgb_free(msg);
+}
+
+/* Endpoint to handle BSSMAP reset acknowlegement */
+static void bssmap_rx_reset_ack(const struct osmo_sccp_user *scu, const struct a_conn_info *a_conn_info,
+				struct msgb *msg)
+{
+
+	struct gsm_network *network = a_conn_info->network;
+	struct osmo_ss7_instance *ss7;
+
+	ss7 = osmo_ss7_instance_find(network->a.cs7_instance);
+	OSMO_ASSERT(ss7);
+
+	if (a_conn_info->reset == NULL) {
+		LOGP(DMSC, LOGL_ERROR, "Received RESET ACK from an unknown BSC %s, ignoring...\n",
+		     osmo_sccp_addr_name(ss7, a_conn_info->bsc_addr));
+		goto fail;
+	}
+
+	LOGP(DMSC, LOGL_NOTICE, "Received RESET ACK from BSC %s\n", osmo_sccp_addr_name(ss7, a_conn_info->bsc_addr));
+
+	/* Confirm that we managed to get the reset ack message
+	 * towards the connection reset logic */
+	a_reset_ack_confirm(a_conn_info->reset);
+
+fail:
+	msgb_free(msg);
+}
+
+/* Handle UNITDATA BSSMAP messages */
+static void bssmap_rcvmsg_udt(struct osmo_sccp_user *scu, const struct a_conn_info *a_conn_info, struct msgb *msg)
+{
+	/* Note: When in the MSC role, RESET ACK is the only valid message that
+	 * can be received via UNITDATA */
+
+	if (msgb_l3len(msg) < 1) {
+		LOGP(DMSC, LOGL_NOTICE, "Error: No data received -- discarding message!\n");
+		return;
+	}
+
+	LOGP(DMSC, LOGL_NOTICE, "Rx BSC UDT BSSMAP %s\n", gsm0808_bssmap_name(msg->l3h[0]));
+
+	switch (msg->l3h[0]) {
+	case BSS_MAP_MSG_RESET:
+		bssmap_rx_reset(scu, a_conn_info, msg);
+		break;
+	case BSS_MAP_MSG_RESET_ACKNOWLEDGE:
+		bssmap_rx_reset_ack(scu, a_conn_info, msg);
+		break;
+	default:
+		LOGP(DMSC, LOGL_NOTICE, "Unimplemented message format: %s -- message discarded!\n",
+		     gsm0808_bssmap_name(msg->l3h[0]));
+		msgb_free(msg);
+	}
+}
+
+/* Receive incoming connection less data messages via sccp */
+void sccp_rx_udt(struct osmo_sccp_user *scu, const struct a_conn_info *a_conn_info, struct msgb *msg)
+{
+	/* Note: The only valid message type that can be received
+	 * via UNITDATA are BSS Management messages */
+	struct bssmap_header *bs;
+
+	OSMO_ASSERT(scu);
+	OSMO_ASSERT(a_conn_info);
+	OSMO_ASSERT(msg);
+
+	LOGP(DMSC, LOGL_NOTICE, "Rx BSC UDT: %s\n", osmo_hexdump(msgb_l2(msg), msgb_l2len(msg)));
+
+	if (msgb_l2len(msg) < sizeof(*bs)) {
+		LOGP(DMSC, LOGL_ERROR, "Error: Header is too short -- discarding message!\n");
+		msgb_free(msg);
+		return;
+	}
+
+	bs = (struct bssmap_header *)msgb_l2(msg);
+	if (bs->length < msgb_l2len(msg) - sizeof(*bs)) {
+		LOGP(DMSC, LOGL_ERROR, "Error: Message is too short -- discarding message!\n");
+		msgb_free(msg);
+		return;
+	}
+
+	switch (bs->type) {
+	case BSSAP_MSG_BSS_MANAGEMENT:
+		msg->l3h = &msg->l2h[sizeof(struct bssmap_header)];
+		bssmap_rcvmsg_udt(scu, a_conn_info, msg);
+		break;
+	default:
+		LOGP(DMSC, LOGL_ERROR,
+		     "Error: Unimplemented message type: %s -- message discarded!\n", gsm0808_bssmap_name(bs->type));
+		msgb_free(msg);
+	}
+}
+
+/*
+ * BSSMAP handling for connection oriented data
+ */
+
+/* Endpoint to handle BSSMAP clear request */
+static int bssmap_rx_clear_rqst(struct osmo_sccp_user *scu, const struct a_conn_info *a_conn_info, struct msgb *msg)
+{
+	struct gsm_network *network = a_conn_info->network;
+	struct tlv_parsed tp;
+	int rc;
+	struct msgb *msg_resp;
+	uint8_t cause;
+	struct gsm_subscriber_connection *conn;
+
+	LOGP(DMSC, LOGL_NOTICE, "BSC requested to clear connection (conn_id=%i)\n", a_conn_info->conn_id);
+
+	tlv_parse(&tp, gsm0808_att_tlvdef(), msg->l3h + 1, msgb_l3len(msg) - 1, 0, 0);
+	if (!TLVP_PRESENT(&tp, GSM0808_IE_CAUSE)) {
+		LOGP(DMSC, LOGL_ERROR, "Cause code is missing -- discarding message!\n");
+		goto fail;
+	}
+	cause = TLVP_VAL(&tp, GSM0808_IE_CAUSE)[0];
+
+	/* Respond with clear command */
+	msg_resp = gsm0808_create_clear_command(GSM0808_CAUSE_CALL_CONTROL);
+	rc = osmo_sccp_tx_data_msg(scu, a_conn_info->conn_id, msg_resp);
+
+	/* If possible, inform the MSC about the clear request */
+	conn = subscr_conn_lookup_a(network, a_conn_info->conn_id);
+	if (!conn)
+		goto fail;
+	msc_clear_request(conn, cause);
+
+	msgb_free(msg);
+	return rc;
+
+fail:
+	msgb_free(msg);
+	return -EINVAL;
+}
+
+/* Endpoint to handle BSSMAP clear complete */
+static int bssmap_rx_clear_complete(struct osmo_sccp_user *scu, const struct a_conn_info *a_conn_info, struct msgb *msg)
+{
+	int rc;
+
+	LOGP(DMSC, LOGL_NOTICE, "Releasing connection (conn_id=%i)\n", a_conn_info->conn_id);
+	rc = osmo_sccp_tx_disconn(scu, a_conn_info->conn_id,
+				  a_conn_info->msc_addr, SCCP_RELEASE_CAUSE_END_USER_ORIGINATED);
+
+	/* Remove the record from the list with active connections. */
+	a_delete_bsc_con(a_conn_info->conn_id);
+
+	msgb_free(msg);
+	return rc;
+}
+
+/* Endpoint to handle layer 3 complete messages */
+static int bssmap_rx_l3_compl(struct osmo_sccp_user *scu, const struct a_conn_info *a_conn_info, struct msgb *msg)
+{
+	struct tlv_parsed tp;
+	struct {
+		uint8_t ident;
+		struct gsm48_loc_area_id lai;
+		uint16_t ci;
+	} __attribute__ ((packed)) lai_ci;
+	uint16_t mcc;
+	uint16_t mnc;
+	uint16_t lac;
+	uint8_t data_length;
+	const uint8_t *data;
+	int rc;
+
+	struct gsm_network *network = a_conn_info->network;
+	struct gsm_subscriber_connection *conn;
+
+	LOGP(DMSC, LOGL_NOTICE, "BSC has completed layer 3 connection (conn_id=%i)\n", a_conn_info->conn_id);
+
+	tlv_parse(&tp, gsm0808_att_tlvdef(), msg->l3h + 1, msgb_l3len(msg) - 1, 0, 0);
+	if (!TLVP_PRESENT(&tp, GSM0808_IE_CELL_IDENTIFIER)) {
+		LOGP(DMSC, LOGL_ERROR, "Mandatory CELL IDENTIFIER not present -- discarding message!\n");
+		goto fail;
+	}
+	if (!TLVP_PRESENT(&tp, GSM0808_IE_LAYER_3_INFORMATION)) {
+		LOGP(DMSC, LOGL_ERROR, "Mandatory LAYER 3 INFORMATION not present -- discarding message!\n");
+		goto fail;
+	}
+
+	/* Parse Cell ID element */
+	/* FIXME: Encapsulate this in a parser/generator function inside
+	 * libosmocore, add support for all specified cell identification
+	 * discriminators (see 3GPP ts 3.2.2.17 Cell Identifier) */
+	data_length = TLVP_LEN(&tp, GSM0808_IE_CELL_IDENTIFIER);
+	data = TLVP_VAL(&tp, GSM0808_IE_CELL_IDENTIFIER);
+	if (sizeof(lai_ci) != data_length) {
+		LOGP(DMSC, LOGL_ERROR,
+		     "Unable to parse element CELL IDENTIFIER (wrong field length) -- discarding message!\n");
+		goto fail;
+	}
+	memcpy(&lai_ci, data, sizeof(lai_ci));
+	if (lai_ci.ident != CELL_IDENT_WHOLE_GLOBAL) {
+		LOGP(DMSC, LOGL_ERROR,
+		     "Unable to parse element CELL IDENTIFIER (wrong cell identification discriminator) -- discarding message!\n");
+		goto fail;
+	}
+	if (gsm48_decode_lai(&lai_ci.lai, &mcc, &mnc, &lac) != 0) {
+		LOGP(DMSC, LOGL_ERROR,
+		     "Unable to parse element CELL IDENTIFIER (lai decoding failed) -- discarding message!\n");
+		goto fail;
+	}
+
+	/* Parse Layer 3 Information element */
+	/* FIXME: This is probably to hackish, compiler also complains "assignment discards ‘const’ qualifier..." */
+	msg->l3h = TLVP_VAL(&tp, GSM0808_IE_LAYER_3_INFORMATION);
+	msg->tail = msg->l3h + TLVP_LEN(&tp, GSM0808_IE_LAYER_3_INFORMATION);
+
+	/* Create new subscriber context */
+	conn = subscr_conn_allocate_a(a_conn_info, network, lac, scu, a_conn_info->conn_id);
+
+	/* Handover location update to the MSC code */
+	/* msc_compl_l3() takes ownership of dtap_msg
+	 * message buffer */
+	rc = msc_compl_l3(conn, msg, 0);
+	if (rc == MSC_CONN_ACCEPT) {
+		LOGP(DMSC, LOGL_NOTICE, "User has been accepted by MSC.\n");
+		return 0;
+	} else if (rc == MSC_CONN_REJECT)
+		LOGP(DMSC, LOGL_NOTICE, "User has been rejected by MSC.\n");
+	else
+		LOGP(DMSC, LOGL_NOTICE, "User has been rejected by MSC (unknown error)\n");
+
+	return -EINVAL;
+
+fail:
+	msgb_free(msg);
+	return -EINVAL;
+}
+
+/* Endpoint to handle BSSMAP classmark update */
+static int bssmap_rx_classmark_upd(struct osmo_sccp_user *scu, const struct a_conn_info *a_conn_info, struct msgb *msg)
+{
+	struct gsm_network *network = a_conn_info->network;
+	struct gsm_subscriber_connection *conn;
+	struct tlv_parsed tp;
+	const uint8_t *cm2 = NULL;
+	const uint8_t *cm3 = NULL;
+	uint8_t cm2_len = 0;
+	uint8_t cm3_len = 0;
+
+	conn = subscr_conn_lookup_a(network, a_conn_info->conn_id);
+	if (!conn)
+		goto fail;
+
+	LOGP(DMSC, LOGL_NOTICE, "BSC sends clasmark update (conn_id=%i)\n", conn->a.conn_id);
+
+	tlv_parse(&tp, gsm0808_att_tlvdef(), msg->l3h + 1, msgb_l3len(msg) - 1, 0, 0);
+	if (!TLVP_PRESENT(&tp, GSM0808_IE_CLASSMARK_INFORMATION_T2)) {
+		LOGP(DMSC, LOGL_ERROR, "Mandatory Classmark Information Type 2 not present -- discarding message!\n");
+		goto fail;
+	}
+
+	cm2 = TLVP_VAL(&tp, GSM0808_IE_CLASSMARK_INFORMATION_T2);
+	cm2_len = TLVP_LEN(&tp, GSM0808_IE_CLASSMARK_INFORMATION_T2);
+
+	if (TLVP_PRESENT(&tp, GSM0808_IE_CLASSMARK_INFORMATION_T3)) {
+		cm3 = TLVP_VAL(&tp, GSM0808_IE_CLASSMARK_INFORMATION_T3);
+		cm3_len = TLVP_LEN(&tp, GSM0808_IE_CLASSMARK_INFORMATION_T3);
+	}
+
+	/* Inform MSC about the classmark change */
+	msc_classmark_chg(conn, cm2, cm2_len, cm3, cm3_len);
+
+	msgb_free(msg);
+	return 0;
+
+fail:
+	msgb_free(msg);
+	return -EINVAL;
+}
+
+/* Endpoint to handle BSSMAP cipher mode complete */
+static int bssmap_rx_ciph_compl(const struct osmo_sccp_user *scu, const struct a_conn_info *a_conn_info,
+				struct msgb *msg)
+{
+	/* FIXME: The field GSM0808_IE_LAYER_3_MESSAGE_CONTENTS is optional by
+	 * means of the specification. So there can be messages without L3 info.
+	 * In this case, the code will crash becrause msc_cipher_mode_compl()
+	 * is not able to deal with msg = NULL and apperently
+	 * msc_cipher_mode_compl() was never meant to be used without L3 data.
+	 * This needs to be discussed further! */
+
+	struct gsm_network *network = a_conn_info->network;
+	struct gsm_subscriber_connection *conn;
+	struct tlv_parsed tp;
+	uint8_t alg_id = 1;
+
+	conn = subscr_conn_lookup_a(network, a_conn_info->conn_id);
+	if (!conn)
+		goto fail;
+
+	LOGP(DMSC, LOGL_NOTICE, "BSC sends cipher mode complete (conn_id=%i)\n", conn->a.conn_id);
+
+	tlv_parse(&tp, gsm0808_att_tlvdef(), msg->l3h + 1, msgb_l3len(msg) - 1, 0, 0);
+
+	if (TLVP_PRESENT(&tp, GSM0808_IE_CHOSEN_ENCR_ALG)) {
+		alg_id = TLVP_VAL(&tp, GSM0808_IE_CHOSEN_ENCR_ALG)[0] - 1;
+	}
+
+	if (TLVP_PRESENT(&tp, GSM0808_IE_LAYER_3_MESSAGE_CONTENTS)) {
+		msg->l3h = TLVP_VAL(&tp, GSM0808_IE_LAYER_3_MESSAGE_CONTENTS);
+		msg->tail = msg->l3h + TLVP_LEN(&tp, GSM0808_IE_LAYER_3_MESSAGE_CONTENTS);
+	} else {
+		msgb_free(msg);
+		msg = NULL;
+	}
+
+	/* Hand over cipher mode complete message to the MSC,
+	 * msc_cipher_mode_compl() takes ownership for msg */
+	msc_cipher_mode_compl(conn, msg, alg_id);
+
+	return 0;
+fail:
+	msgb_free(msg);
+	return -EINVAL;
+}
+
+/* Endpoint to handle BSSMAP cipher mode reject */
+static int bssmap_rx_ciph_rej(const struct osmo_sccp_user *scu, const struct a_conn_info *a_conn_info, struct msgb *msg)
+{
+	struct gsm_network *network = a_conn_info->network;
+	struct gsm_subscriber_connection *conn;
+	struct tlv_parsed tp;
+	uint8_t cause;
+
+	conn = subscr_conn_lookup_a(network, a_conn_info->conn_id);
+	if (!conn)
+		goto fail;
+
+	LOGP(DMSC, LOGL_NOTICE, "BSC sends cipher mode reject (conn_id=%i)\n", conn->a.conn_id);
+
+	tlv_parse(&tp, gsm0808_att_tlvdef(), msg->l3h + 1, msgb_l3len(msg) - 1, 0, 0);
+	if (!TLVP_PRESENT(&tp, BSS_MAP_MSG_CIPHER_MODE_REJECT)) {
+		LOGP(DMSC, LOGL_ERROR, "Cause code is missing -- discarding message!\n");
+		goto fail;
+	}
+
+	cause = TLVP_VAL(&tp, BSS_MAP_MSG_CIPHER_MODE_REJECT)[0];
+	LOGP(DMSC, LOGL_NOTICE, "Cipher mode rejection cause: %i\n", cause);
+
+	/* FIXME: Can we do something meaningful here? e.g. report to the
+	 * msc code somehow that the cipher mode command has failed. */
+
+	msgb_free(msg);
+	return 0;
+fail:
+	msgb_free(msg);
+	return -EINVAL;
+}
+
+/* Endpoint to handle BSSMAP assignment failure */
+static int bssmap_rx_ass_fail(const struct osmo_sccp_user *scu, const struct a_conn_info *a_conn_info, struct msgb *msg)
+{
+	struct gsm_network *network = a_conn_info->network;
+	struct gsm_subscriber_connection *conn;
+	struct tlv_parsed tp;
+	uint8_t cause;
+	uint8_t *rr_cause_ptr = NULL;
+	uint8_t rr_cause;
+
+	conn = subscr_conn_lookup_a(network, a_conn_info->conn_id);
+	if (!conn)
+		goto fail;
+
+	LOGP(DMSC, LOGL_NOTICE, "BSC sends assignment failure message (conn_id=%i)\n", conn->a.conn_id);
+
+	tlv_parse(&tp, gsm0808_att_tlvdef(), msg->l3h + 1, msgb_l3len(msg) - 1, 0, 0);
+	if (!TLVP_PRESENT(&tp, GSM0808_IE_CAUSE)) {
+		LOGP(DMSC, LOGL_ERROR, "Cause code is missing -- discarding message!\n");
+		goto fail;
+	}
+	cause = TLVP_VAL(&tp, GSM0808_IE_CAUSE)[0];
+
+	if (TLVP_PRESENT(&tp, GSM0808_IE_RR_CAUSE)) {
+		rr_cause = TLVP_VAL(&tp, GSM0808_IE_RR_CAUSE)[0];
+		rr_cause_ptr = &rr_cause;
+	}
+
+	/* FIXME: In AoIP, the Assignment failure will carry also an optional
+	 * Codec List (BSS Supported) element. It has to be discussed if we
+	 * can ignore this element. If not, The msc_assign_fail() function
+	 * call has to change. However msc_assign_fail() does nothing in the
+	 * end. So probably we can just leave it as it is. Even for AoIP */
+
+	/* Inform the MSC about the assignment failure event */
+	msc_assign_fail(conn, cause, rr_cause_ptr);
+
+	msgb_free(msg);
+	return 0;
+fail:
+	msgb_free(msg);
+	return -EINVAL;
+}
+
+/* Endpoint to handle sapi "n" reject */
+static int bssmap_rx_sapi_n_rej(const struct osmo_sccp_user *scu, const struct a_conn_info *a_conn_info,
+				struct msgb *msg)
+{
+	struct gsm_network *network = a_conn_info->network;
+	struct gsm_subscriber_connection *conn;
+	struct tlv_parsed tp;
+	uint8_t dlci;
+
+	conn = subscr_conn_lookup_a(network, a_conn_info->conn_id);
+	if (!conn)
+		goto fail;
+
+	LOGP(DMSC, LOGL_NOTICE, "BSC sends sapi \"n\" reject message (conn_id=%i)\n", conn->a.conn_id);
+
+	/* Note: The MSC code seems not to care about the cause code, but by
+	 * the specification it is mandatory, so we check its presence. See
+	 * also 3GPP TS 48.008 3.2.1.34 SAPI "n" REJECT */
+	tlv_parse(&tp, gsm0808_att_tlvdef(), msg->l3h + 1, msgb_l3len(msg) - 1, 0, 0);
+	if (!TLVP_PRESENT(&tp, GSM0808_IE_CAUSE)) {
+		LOGP(DMSC, LOGL_ERROR, "Cause code is missing -- discarding message!\n");
+		goto fail;
+	}
+
+	tlv_parse(&tp, gsm0808_att_tlvdef(), msg->l3h + 1, msgb_l3len(msg) - 1, 0, 0);
+	if (!TLVP_PRESENT(&tp, GSM0808_IE_DLCI)) {
+		LOGP(DMSC, LOGL_ERROR, "DLCI is missing -- discarding message!\n");
+		goto fail;
+	}
+	dlci = TLVP_VAL(&tp, GSM0808_IE_DLCI)[0];
+
+	/* Inform the MSC about the sapi "n" reject event */
+	msc_sapi_n_reject(conn, dlci);
+
+	msgb_free(msg);
+	return 0;
+fail:
+	msgb_free(msg);
+	return -EINVAL;
+}
+
+/* Endpoint to handle assignment complete */
+static int bssmap_rx_ass_compl(const struct osmo_sccp_user *scu, const struct a_conn_info *a_conn_info,
+			       struct msgb *msg)
+{
+	struct gsm_network *network = a_conn_info->network;
+	struct gsm_subscriber_connection *conn;
+	struct mgcpgw_client *mgcp;
+	struct tlv_parsed tp;
+	struct sockaddr_storage rtp_addr;
+	struct sockaddr_in *rtp_addr_in;
+	int rc;
+
+	conn = subscr_conn_lookup_a(network, a_conn_info->conn_id);
+	if (!conn)
+		goto fail;
+
+	mgcp = conn->network->mgcpgw.client;
+	OSMO_ASSERT(mgcp);
+
+	LOGP(DMSC, LOGL_NOTICE, "BSC sends assignment complete message (conn_id=%i)\n", conn->a.conn_id);
+
+	tlv_parse(&tp, gsm0808_att_tlvdef(), msg->l3h + 1, msgb_l3len(msg) - 1, 0, 0);
+
+	if (!TLVP_PRESENT(&tp, GSM0808_IE_AOIP_TRASP_ADDR)) {
+		LOGP(DMSC, LOGL_ERROR, "AoIP transport identifier missing -- discarding message!\n");
+		goto fail;
+	}
+
+	/* Decode AoIP transport address element */
+	rc = gsm0808_dec_aoip_trasp_addr(&rtp_addr, TLVP_VAL(&tp, GSM0808_IE_AOIP_TRASP_ADDR),
+					 TLVP_LEN(&tp, GSM0808_IE_AOIP_TRASP_ADDR));
+	if (rc < 0) {
+		LOGP(DMSC, LOGL_ERROR, "Unable to decode aoip transport address.\n");
+		goto fail;
+	}
+
+	/* use address / port supplied with the AoIP
+	 * transport address element */
+	if (rtp_addr.ss_family == AF_INET) {
+		rtp_addr_in = (struct sockaddr_in *)&rtp_addr;
+		conn->rtp.port_subscr = osmo_ntohs(rtp_addr_in->sin_port);
+		/* FIXME: We also get the IP-Address of the remote (e.g. BTS)
+		 * end with the response. Currently we just ignore that address.
+		 * Instead we expect that our local MGCP gateway and the code
+		 * controlling it, magically knows the IP of the remote end. */
+	} else {
+		LOGP(DMSC, LOGL_ERROR, "Unsopported addressing scheme. (supports only IPV4)\n");
+		goto fail;
+	}
+
+	/* FIXME: Seems to be related to authentication or,
+	   encryption. Is this really in the right place? */
+	msc_rx_sec_mode_compl(conn);
+
+	msgb_free(msg);
+	return 0;
+fail:
+	msgb_free(msg);
+	return -EINVAL;
+}
+
+/* Handle incoming connection oriented BSSMAP messages */
+static int rx_bssmap(struct osmo_sccp_user *scu, const struct a_conn_info *a_conn_info, struct msgb *msg)
+{
+	if (msgb_l3len(msg) < 1) {
+		LOGP(DMSC, LOGL_NOTICE, "Error: No data received -- discarding message!\n");
+		msgb_free(msg);
+		return -1;
+	}
+
+	LOGP(DMSC, LOGL_NOTICE, "Rx MSC DT1 BSSMAP %s\n", gsm0808_bssmap_name(msg->l3h[0]));
+
+	switch (msg->l3h[0]) {
+	case BSS_MAP_MSG_CLEAR_RQST:
+		return bssmap_rx_clear_rqst(scu, a_conn_info, msg);
+		break;
+	case BSS_MAP_MSG_CLEAR_COMPLETE:
+		return bssmap_rx_clear_complete(scu, a_conn_info, msg);
+		break;
+	case BSS_MAP_MSG_COMPLETE_LAYER_3:
+		return bssmap_rx_l3_compl(scu, a_conn_info, msg);
+		break;
+	case BSS_MAP_MSG_CLASSMARK_UPDATE:
+		return bssmap_rx_classmark_upd(scu, a_conn_info, msg);
+		break;
+	case BSS_MAP_MSG_CIPHER_MODE_COMPLETE:
+		return bssmap_rx_ciph_compl(scu, a_conn_info, msg);
+		break;
+	case BSS_MAP_MSG_CIPHER_MODE_REJECT:
+		return bssmap_rx_ciph_rej(scu, a_conn_info, msg);
+		break;
+	case BSS_MAP_MSG_ASSIGMENT_FAILURE:
+		return bssmap_rx_ass_fail(scu, a_conn_info, msg);
+		break;
+	case BSS_MAP_MSG_SAPI_N_REJECT:
+		return bssmap_rx_sapi_n_rej(scu, a_conn_info, msg);
+		break;
+	case BSS_MAP_MSG_ASSIGMENT_COMPLETE:
+		return bssmap_rx_ass_compl(scu, a_conn_info, msg);
+		break;
+	default:
+		LOGP(DMSC, LOGL_ERROR, "Unimplemented msg type: %s\n", gsm0808_bssmap_name(msg->l3h[0]));
+		msgb_free(msg);
+		return -EINVAL;
+	}
+
+	return -EINVAL;
+}
+
+/* Endpoint to handle regular BSSAP DTAP messages */
+static int rx_dtap(const struct osmo_sccp_user *scu, const struct a_conn_info *a_conn_info, struct msgb *msg)
+{
+	struct gsm_network *network = a_conn_info->network;
+	struct gsm_subscriber_connection *conn;
+
+	conn = subscr_conn_lookup_a(network, a_conn_info->conn_id);
+	if (!conn) {
+		msgb_free(msg);
+		return -EINVAL;
+	}
+
+	LOGP(DMSC, LOGL_NOTICE, "BSC sends layer 3 dtap (conn_id=%i)\n", conn->a.conn_id);
+
+	/* msc_dtap expects the dtap payload in l3h */
+	msg->l3h = msg->l2h + 3;
+
+	/* Forward dtap payload into the msc,
+	 * msc_dtap() takes ownership for msg */
+	msc_dtap(conn, conn->a.conn_id, msg);
+
+	return 0;
+}
+
+/* Handle incoming connection oriented messages */
+int sccp_rx_dt(struct osmo_sccp_user *scu, const struct a_conn_info *a_conn_info, struct msgb *msg)
+{
+	OSMO_ASSERT(scu);
+	OSMO_ASSERT(a_conn_info);
+	OSMO_ASSERT(msg);
+
+	LOGP(DMSC, LOGL_NOTICE, "Rx BSC DT: %s\n", osmo_hexdump(msgb_l2(msg), msgb_l2len(msg)));
+
+	if (msgb_l2len(msg) < sizeof(struct bssmap_header)) {
+		LOGP(DMSC, LOGL_NOTICE, "The header is too short -- discarding message!\n");
+		msgb_free(msg);
+	}
+
+	switch (msg->l2h[0]) {
+	case BSSAP_MSG_BSS_MANAGEMENT:
+		msg->l3h = &msg->l2h[sizeof(struct bssmap_header)];
+		return rx_bssmap(scu, a_conn_info, msg);
+		break;
+	case BSSAP_MSG_DTAP:
+		return rx_dtap(scu, a_conn_info, msg);
+		break;
+	default:
+		LOGP(DMSC, LOGL_ERROR, "Unimplemented BSSAP msg type: %s\n", gsm0808_bssap_name(msg->l2h[0]));
+		msgb_free(msg);
+		return -EINVAL;
+	}
+
+	return -EINVAL;
+}
diff --git a/src/libmsc/gsm_04_08.c b/src/libmsc/gsm_04_08.c
index 28cba5b..b6746a5 100644
--- a/src/libmsc/gsm_04_08.c
+++ b/src/libmsc/gsm_04_08.c
@@ -79,6 +79,8 @@
 #include <openbsc/iu.h>
 #endif
 
+#include <openbsc/a_iface.h>
+
 #include <assert.h>
 
 
@@ -1267,6 +1269,8 @@
 	struct msgb *msg;
 	unsigned char *data;
 
+	DEBUGP(DMNCC, "transmit message %s\n", get_mncc_name(msg_type));
+
 #if BEFORE_MSCSPLIT
 	/* Re-enable this log output once we can obtain this information via
 	 * A-interface, see OS#2391. */
@@ -1324,6 +1328,9 @@
 {
 	gsm48_stop_cc_timer(trans);
 
+	/* Make sure call also gets released on the mgcp side */
+	msc_call_release(trans);
+
 	/* send release to L4, if callref still exists */
 	if (trans->callref) {
 		/* Ressource unavailable */
@@ -1549,6 +1556,12 @@
 		setup.fields |= MNCC_F_BEARER_CAP;
 		gsm48_decode_bearer_cap(&setup.bearer_cap,
 				  TLVP_VAL(&tp, GSM48_IE_BEARER_CAP)-1);
+
+		/* Create a copy of the bearer capability
+		 * in the transaction struct, so we can use
+		 * this information later */
+		memcpy(&trans->bearer_cap,&setup.bearer_cap,
+		       sizeof(trans->bearer_cap));
 	}
 	/* facility */
 	if (TLVP_PRESENT(&tp, GSM48_IE_FACILITY)) {
@@ -1682,6 +1695,7 @@
 	unsigned int payload_len = msgb_l3len(msg) - sizeof(*gh);
 	struct tlv_parsed tp;
 	struct gsm_mncc call_conf;
+	int rc;
 
 	gsm48_stop_cc_timer(trans);
 	gsm48_start_cc_timer(trans, 0x310, GSM48_T310);
@@ -1702,6 +1716,12 @@
 		call_conf.fields |= MNCC_F_BEARER_CAP;
 		gsm48_decode_bearer_cap(&call_conf.bearer_cap,
 				  TLVP_VAL(&tp, GSM48_IE_BEARER_CAP)-1);
+
+		/* Create a copy of the bearer capability
+		 * in the transaction struct, so we can use
+		 * this information later */
+		memcpy(&trans->bearer_cap,&call_conf.bearer_cap,
+		       sizeof(trans->bearer_cap));
 	}
 	/* cause */
 	if (TLVP_PRESENT(&tp, GSM48_IE_CAUSE)) {
@@ -1721,7 +1741,18 @@
 
 	new_cc_state(trans, GSM_CSTATE_MO_TERM_CALL_CONF);
 
-	msc_call_assignment(trans);
+	/* Assign call (if not done yet) */
+	if (trans->assignment_done == false) {
+		rc = msc_call_assignment(trans);
+		trans->assignment_done = true;
+	}
+	else
+		rc = 0;
+
+	/* don't continue, if there were problems with
+	 * the call assignment. */
+	if (rc)
+		return rc;
 
 	return mncc_recvmsg(trans->net, trans, MNCC_CALL_CONF_IND,
 			    &call_conf);
@@ -1752,7 +1783,15 @@
 	if (rc)
 		return rc;
 
-	return msc_call_assignment(trans);
+	/* Assign call (if not done yet) */
+	if (trans->assignment_done == false) {
+		rc = msc_call_assignment(trans);
+		trans->assignment_done = true;
+	}
+	else
+		rc = 0;
+
+	return rc;
 }
 
 static int gsm48_cc_rx_alerting(struct gsm_trans *trans, struct msgb *msg)
@@ -2398,6 +2437,12 @@
 		modify.fields |= MNCC_F_BEARER_CAP;
 		gsm48_decode_bearer_cap(&modify.bearer_cap,
 				  TLVP_VAL(&tp, GSM48_IE_BEARER_CAP)-1);
+
+		/* Create a copy of the bearer capability
+		 * in the transaction struct, so we can use
+		 * this information later */
+		memcpy(&trans->bearer_cap,&modify.bearer_cap,
+		       sizeof(trans->bearer_cap));
 	}
 
 	new_cc_state(trans, GSM_CSTATE_MO_ORIG_MODIFY);
@@ -2440,6 +2485,12 @@
 		modify.fields |= MNCC_F_BEARER_CAP;
 		gsm48_decode_bearer_cap(&modify.bearer_cap,
 				  TLVP_VAL(&tp, GSM48_IE_BEARER_CAP)-1);
+
+		/* Create a copy of the bearer capability
+		 * in the transaction struct, so we can use
+		 * this information later */
+		memcpy(&trans->bearer_cap,&modify.bearer_cap,
+		       sizeof(trans->bearer_cap));
 	}
 
 	new_cc_state(trans, GSM_CSTATE_ACTIVE);
@@ -2480,6 +2531,12 @@
 		modify.fields |= GSM48_IE_BEARER_CAP;
 		gsm48_decode_bearer_cap(&modify.bearer_cap,
 				  TLVP_VAL(&tp, GSM48_IE_BEARER_CAP)-1);
+
+		/* Create a copy of the bearer capability
+		 * in the transaction struct, so we can use
+		 * this information later */
+		memcpy(&trans->bearer_cap,&modify.bearer_cap,
+		       sizeof(trans->bearer_cap));
 	}
 	/* cause */
 	if (TLVP_PRESENT(&tp, GSM48_IE_CAUSE)) {
@@ -2582,6 +2639,139 @@
 	return mncc_recvmsg(trans->net, trans, MNCC_USERINFO_IND, &user);
 }
 
+static void mncc_recv_rtp(struct gsm_network *net, uint32_t callref,
+		int cmd, uint32_t addr, uint16_t port, uint32_t payload_type,
+		uint32_t payload_msg_type)
+{
+	uint8_t data[sizeof(struct gsm_mncc)];
+	struct gsm_mncc_rtp *rtp;
+
+	memset(&data, 0, sizeof(data));
+	rtp = (struct gsm_mncc_rtp *) &data[0];
+
+	rtp->callref = callref;
+	rtp->msg_type = cmd;
+	rtp->ip = addr;
+	rtp->port = port;
+	rtp->payload_type = payload_type;
+	rtp->payload_msg_type = payload_msg_type;
+	mncc_recvmsg(net, NULL, cmd, (struct gsm_mncc *)data);
+}
+
+static void mncc_recv_rtp_sock(struct gsm_network *net, struct gsm_trans *trans, int cmd)
+{
+	int msg_type;
+
+	/* FIXME This has to be set to some meaningful value.
+	 * Possible options are:
+	 * GSM_TCHF_FRAME, GSM_TCHF_FRAME_EFR,
+	 * GSM_TCHH_FRAME, GSM_TCH_FRAME_AMR
+	 * (0 if unknown) */
+	msg_type = GSM_TCHF_FRAME;
+
+	uint32_t addr = mgcpgw_client_remote_addr_n(net->mgcpgw.client);
+	uint16_t port = trans->conn->rtp.port_cn;
+
+	/* FIXME: This has to be set to some meaningful value,
+	 * before the MSC-Split, this value was pulled from
+	 * lchan->abis_ip.rtp_payload */
+	uint32_t payload_type = 0;
+
+	return mncc_recv_rtp(net, trans->callref, cmd,
+			addr,
+			port,
+		        payload_type,
+			msg_type);
+}
+
+static void mncc_recv_rtp_err(struct gsm_network *net, uint32_t callref, int cmd)
+{
+	return mncc_recv_rtp(net, callref, cmd, 0, 0, 0, 0);
+}
+
+static int tch_rtp_create(struct gsm_network *net, uint32_t callref)
+{
+	struct gsm_trans *trans;
+	int rc;
+
+	/* Find callref */
+	trans = trans_find_by_callref(net, callref);
+	if (!trans) {
+		LOGP(DMNCC, LOGL_ERROR, "RTP create for non-existing trans\n");
+		mncc_recv_rtp_err(net, callref, MNCC_RTP_CREATE);
+		return -EIO;
+	}
+	log_set_context(LOG_CTX_VLR_SUBSCR, trans->vsub);
+	if (!trans->conn) {
+		LOGP(DMNCC, LOGL_NOTICE, "RTP create for trans without conn\n");
+		mncc_recv_rtp_err(net, callref, MNCC_RTP_CREATE);
+		return 0;
+	}
+
+	trans->conn->mncc_rtp_bridge = 1;
+
+	/* When we call msc_call_assignment() we will trigger, depending
+	 * on the RAN type the call assignment on the A or Iu interface.
+	 * msc_call_assignment() also takes care about sending the CRCX
+	 * command to the MGCP-GW. The CRCX will return the port number,
+	 * where the PBX (e.g. Asterisk) will send its RTP stream to. We
+	 * have to return this port number back to the MNCC by sending
+	 * it back with the TCH_RTP_CREATE message. To make sure that
+	 * this message is sent AFTER the response to CRCX from the
+	 * MGCP-GW has arrived, we need will instruct msc_call_assignment()
+	 * to take care of this by setting trans->tch_rtp_create to true.
+	 * This will make sure that gsm48_tch_rtp_create() (below) is
+	 * called as soon as the local port number has become known. */
+	trans->tch_rtp_create = true;
+
+	/* Assign call (if not done yet) */
+	if (trans->assignment_done == false) {
+		rc = msc_call_assignment(trans);
+		trans->assignment_done = true;
+	}
+	else
+		rc = 0;
+
+	return rc;
+}
+
+/* Trigger TCH_RTP_CREATE acknowledgement */
+int gsm48_tch_rtp_create(struct gsm_trans *trans)
+{
+	/* This function is called as soon as the port, on which the
+	 * mgcp-gw expects the incoming RTP stream from the remote
+	 * end (e.g. Asterisk) is known. */
+
+	struct gsm_subscriber_connection *conn = trans->conn;
+	struct gsm_network *network = conn->network;
+
+	mncc_recv_rtp_sock(network, trans, MNCC_RTP_CREATE);
+	return 0;
+}
+
+static int tch_rtp_connect(struct gsm_network *net, void *arg)
+{
+	struct gsm_trans *trans;
+	struct gsm_mncc_rtp *rtp = arg;
+
+	/* Find callref */
+	trans = trans_find_by_callref(net, rtp->callref);
+	if (!trans) {
+		LOGP(DMNCC, LOGL_ERROR, "RTP connect for non-existing trans\n");
+		mncc_recv_rtp_err(net, rtp->callref, MNCC_RTP_CONNECT);
+		return -EIO;
+	}
+	log_set_context(LOG_CTX_VLR_SUBSCR, trans->vsub);
+	if (!trans->conn) {
+		LOGP(DMNCC, LOGL_ERROR, "RTP connect for trans without conn\n");
+		mncc_recv_rtp_err(net, rtp->callref, MNCC_RTP_CONNECT);
+		return 0;
+	}
+
+	msc_call_connect(trans,rtp->port,rtp->ip);
+	return 0;
+}
+
 static struct downstate {
 	uint32_t	states;
 	int		type;
@@ -2657,11 +2847,16 @@
 		if (rc < 0)
 			disconnect_bridge(net, arg, -rc);
 		return rc;
+	case MNCC_RTP_CREATE:
+		return tch_rtp_create(net, data->callref);
+	case MNCC_RTP_CONNECT:
+		return tch_rtp_connect(net, arg);
+	case MNCC_RTP_FREE:
+		/* unused right now */
+		return -EIO;
+
 	case MNCC_FRAME_DROP:
 	case MNCC_FRAME_RECV:
-	case MNCC_RTP_CREATE:
-	case MNCC_RTP_CONNECT:
-	case MNCC_RTP_FREE:
 	case GSM_TCHF_FRAME:
 	case GSM_TCHF_FRAME_EFR:
 	case GSM_TCHH_FRAME:
@@ -3211,8 +3406,8 @@
 	case RAN_GERAN_A:
 		DEBUGP(DMM, "-> CIPHER MODE COMMAND %s\n",
 		       vlr_subscr_name(conn->vsub));
-		return msc_gsm0808_tx_cipher_mode(conn, ciph, tuple->vec.kc, 8,
-						  retrieve_imeisv);
+		return a_iface_tx_cipher_mode(conn, ciph, tuple->vec.kc, 8,
+					      retrieve_imeisv);
 	case RAN_UTRAN_IU:
 #ifdef BUILD_IU
 		DEBUGP(DMM, "-> SECURITY MODE CONTROL %s\n",
diff --git a/src/libmsc/gsm_subscriber.c b/src/libmsc/gsm_subscriber.c
index ac6c96a..73361a1 100644
--- a/src/libmsc/gsm_subscriber.c
+++ b/src/libmsc/gsm_subscriber.c
@@ -43,6 +43,7 @@
 #include <openbsc/iu.h>
 #include <openbsc/osmo_msc.h>
 #include <openbsc/msc_ifaces.h>
+#include <openbsc/a_iface.h>
 
 int subscr_paging_dispatch(unsigned int hooknum, unsigned int event,
 			   struct msgb *msg, void *data, void *param)
@@ -105,7 +106,7 @@
 	 * Need to add BSC paging at some point. */
 	switch (vsub->cs.attached_via_ran) {
 	case RAN_GERAN_A:
-		return a_page(vsub->imsi, vsub->tmsi, vsub->lac);
+		return a_iface_tx_paging(vsub->imsi, vsub->tmsi, vsub->lac);
 	case RAN_UTRAN_IU:
 		return iu_page_cs(vsub->imsi,
 				  vsub->tmsi == GSM_RESERVED_TMSI?
diff --git a/src/libmsc/iucs.c b/src/libmsc/iucs.c
index aeda140..be026c8 100644
--- a/src/libmsc/iucs.c
+++ b/src/libmsc/iucs.c
@@ -40,8 +40,8 @@
 {
 	struct gsm_subscriber_connection *conn;
 
-	DEBUGP(DIUCS, "Allocating IuCS subscriber conn: lac %d, link_id %p, conn_id %" PRIx32 "\n",
-	       lac, ue->link, ue->conn_id);
+	DEBUGP(DIUCS, "Allocating IuCS subscriber conn: lac %d, conn_id %" PRIx32 "\n",
+	       lac, ue->conn_id);
 
 	conn = talloc_zero(network, struct gsm_subscriber_connection);
 	if (!conn)
@@ -61,8 +61,7 @@
 {
 	if (a == b)
 		return 1;
-	return (a->link == b->link)
-		&& (a->conn_id == b->conn_id);
+	return (a->conn_id == b->conn_id);
 }
 
 static inline void log_subscribers(struct gsm_network *network)
@@ -78,8 +77,7 @@
 		case RAN_UTRAN_IU:
 			DEBUGPC(DIUCS, " Iu");
 			if (conn->iu.ue_ctx) {
-				DEBUGPC(DIUCS, " link %p, conn_id %d",
-					conn->iu.ue_ctx->link,
+				DEBUGPC(DIUCS, " conn_id %d",
 					conn->iu.ue_ctx->conn_id
 				       );
 			}
@@ -101,7 +99,7 @@
 	DEBUGP(DIUCS, "subscribers registered: %d\n", i);
 }
 
-/* Return an existing IuCS subscriber connection record for the given link and
+/* Return an existing IuCS subscriber connection record for the given
  * connection IDs, or return NULL if not found. */
 struct gsm_subscriber_connection *subscr_conn_lookup_iu(
 						struct gsm_network *network,
@@ -109,8 +107,8 @@
 {
 	struct gsm_subscriber_connection *conn;
 
-	DEBUGP(DIUCS, "Looking for IuCS subscriber: link_id %p, conn_id %" PRIx32 "\n",
-	       ue->link, ue->conn_id);
+	DEBUGP(DIUCS, "Looking for IuCS subscriber: conn_id %" PRIx32 "\n",
+	       ue->conn_id);
 	log_subscribers(network);
 
 	llist_for_each_entry(conn, &network->subscr_conns, entry) {
@@ -118,12 +116,12 @@
 			continue;
 		if (!same_ue_conn(conn->iu.ue_ctx, ue))
 			continue;
-		DEBUGP(DIUCS, "Found IuCS subscriber for link_id %p, conn_id %" PRIx32 "\n",
-		       ue->link, ue->conn_id);
+		DEBUGP(DIUCS, "Found IuCS subscriber for conn_id %" PRIx32 "\n",
+		       ue->conn_id);
 		return conn;
 	}
-	DEBUGP(DIUCS, "No IuCS subscriber found for link_id %p, conn_id %" PRIx32 "\n",
-	       ue->link, ue->conn_id);
+	DEBUGP(DIUCS, "No IuCS subscriber found for conn_id %" PRIx32 "\n",
+	       ue->conn_id);
 	return NULL;
 }
 
diff --git a/src/libmsc/msc_ifaces.c b/src/libmsc/msc_ifaces.c
index 56cbd49..7d2e898 100644
--- a/src/libmsc/msc_ifaces.c
+++ b/src/libmsc/msc_ifaces.c
@@ -29,6 +29,7 @@
 #include <openbsc/mgcp.h>
 #include <openbsc/mgcpgw_client.h>
 #include <openbsc/vlr.h>
+#include <openbsc/a_iface.h>
 
 #include "../../bscconfig.h"
 
@@ -41,13 +42,18 @@
 
 static int msc_tx(struct gsm_subscriber_connection *conn, struct msgb *msg)
 {
+	if (!conn)
+		return -EINVAL;
+	if (!msg)
+		return -EINVAL;
+
 	DEBUGP(DMSC, "msc_tx %u bytes to %s via %s\n",
 	       msg->len, vlr_subscr_name(conn->vsub),
 	       ran_type_name(conn->via_ran));
 	switch (conn->via_ran) {
 	case RAN_GERAN_A:
 		msg->dst = conn;
-		return a_tx(msg);
+		return a_iface_tx_dtap(msg);
 
 	case RAN_UTRAN_IU:
 		msg->dst = conn->iu.ue_ctx;
@@ -72,9 +78,15 @@
 /* 9.2.5 CM service accept */
 int msc_gsm48_tx_mm_serv_ack(struct gsm_subscriber_connection *conn)
 {
-	struct msgb *msg = gsm48_msgb_alloc_name("GSM 04.08 SERV ACC");
-	struct gsm48_hdr *gh = (struct gsm48_hdr *) msgb_put(msg, sizeof(*gh));
+	struct msgb *msg;
+	struct gsm48_hdr *gh;
 
+	if (!conn)
+		return -EINVAL;
+
+	msg = gsm48_msgb_alloc_name("GSM 04.08 SERV ACC");
+
+	gh = (struct gsm48_hdr *) msgb_put(msg, sizeof(*gh));
 	gh->proto_discr = GSM48_PDISC_MM;
 	gh->msg_type = GSM48_MT_MM_CM_SERV_ACC;
 
@@ -89,6 +101,10 @@
 			     enum gsm48_reject_value value)
 {
 	struct msgb *msg;
+
+	if (!conn)
+		return -EINVAL;
+
 	conn->received_cm_service_request = false;
 
 	msg = gsm48_create_mm_serv_rej(value);
@@ -104,6 +120,9 @@
 
 int msc_tx_common_id(struct gsm_subscriber_connection *conn)
 {
+	if (!conn)
+		return -EINVAL;
+
 	/* Common ID is only sent over IuCS */
 	if (conn->via_ran != RAN_UTRAN_IU) {
 		LOGP(DMM, LOGL_INFO,
@@ -118,10 +137,10 @@
 	return iu_tx_common_id(conn->iu.ue_ctx, conn->vsub->imsi);
 }
 
-#ifdef BUILD_IU
-static void iu_rab_act_cs(struct ue_conn_ctx *uectx, uint8_t rab_id,
-			  uint32_t rtp_ip, uint16_t rtp_port)
+static int iu_rab_act_cs(struct ue_conn_ctx *uectx, uint8_t rab_id,
+			 uint32_t rtp_ip, uint16_t rtp_port)
 {
+#ifdef BUILD_IU
 	struct msgb *msg;
 	bool use_x213_nsap;
 	uint32_t conn_id = uectx->conn_id;
@@ -140,6 +159,11 @@
 		LOGP(DIUCS, LOGL_ERROR, "Failed to send RAB Assignment:"
 		     " conn_id=%d rab_id=%d rtp=%x:%u\n",
 		     conn_id, rab_id, rtp_ip, rtp_port);
+	return 0;
+#else
+	LOGP(DMSC, LOGL_ERROR, "Cannot send Iu RAB Assignment: built without Iu support\n");
+	return -ENOTSUP;
+#endif
 }
 
 static void mgcp_response_rab_act_cs_crcx(struct mgcp_response *r, void *priv)
@@ -165,71 +189,75 @@
 		goto rab_act_cs_error;
 	}
 
-	conn->iu.mgcp_rtp_port_cn = r->audio_port;
+	conn->rtp.port_cn = r->audio_port;
 
 	rtp_ip = mgcpgw_client_remote_addr_n(conn->network->mgcpgw.client);
-	iu_rab_act_cs(uectx, conn->iu.rab_id, rtp_ip,
-		      conn->iu.mgcp_rtp_port_ue);
-	/* use_x213_nsap == 0 for ip.access nano3G */
+
+	if (trans->conn->via_ran == RAN_UTRAN_IU) {
+		/* Assign a voice channel via RANAP on 3G */
+		if (iu_rab_act_cs(uectx, conn->iu.rab_id, rtp_ip, conn->rtp.port_subscr))
+			goto rab_act_cs_error;
+	} else if (trans->conn->via_ran == RAN_GERAN_A) {
+		/* Assign a voice channel via A on 2G */
+		if (a_iface_tx_assignment(trans))
+			goto rab_act_cs_error;
+	} else
+		goto rab_act_cs_error;
+
+	/* Respond back to MNCC (if requested) */
+	if (trans->tch_rtp_create) {
+		if (gsm48_tch_rtp_create(trans))
+			goto rab_act_cs_error;
+	}
+	return;
 
 rab_act_cs_error:
 	/* FIXME abort call, invalidate conn, ... */
+	LOGP(DMSC, LOGL_ERROR, "%s: failure during assignment\n",
+	     vlr_subscr_name(trans->vsub));
 	return;
 }
 
-static int conn_iu_rab_act_cs(struct gsm_trans *trans)
+int msc_call_assignment(struct gsm_trans *trans)
 {
-	struct gsm_subscriber_connection *conn = trans->conn;
-	struct mgcpgw_client *mgcp = conn->network->mgcpgw.client;
+	struct gsm_subscriber_connection *conn;
+	struct mgcpgw_client *mgcp;
 	struct msgb *msg;
+	uint16_t bts_base;
 
-	/* HACK. where to scope the RAB Id? At the conn / subscriber /
-	 * ue_conn_ctx? */
-	static uint8_t next_rab_id = 1;
-	conn->iu.rab_id = next_rab_id ++;
+	if (!trans)
+		return -EINVAL;
+	if (!trans->conn)
+		return -EINVAL;
 
-	conn->iu.mgcp_rtp_endpoint =
+	conn = trans->conn;
+	mgcp = conn->network->mgcpgw.client;
+
+#ifdef BUILD_IU
+	/* FIXME: HACK. where to scope the RAB Id? At the conn / subscriber / ue_conn_ctx? */
+	static uint8_t next_iu_rab_id = 1;
+	if (conn->via_ran == RAN_UTRAN_IU)
+		conn->iu.rab_id = next_iu_rab_id ++;
+#endif
+
+	conn->rtp.mgcp_rtp_endpoint =
 		mgcpgw_client_next_endpoint(conn->network->mgcpgw.client);
-	/* HACK: the addresses should be known from CRCX response
-	 * and config. */
-	conn->iu.mgcp_rtp_port_ue = 4000 + 2 * conn->iu.mgcp_rtp_endpoint;
+
+	/* This will calculate the port we assign to the BTS via AoIP
+	 * assignment command (or rab-assignment on 3G) The BTS will send
+	 * its RTP traffic to that port on the MGCPGW side. The MGCPGW only
+	 * gets the endpoint ID via the CRCX. It will do the same calculation
+	 * on his side too to get knowledge of the rtp port. */
+	bts_base = mgcp->actual.bts_base;
+	conn->rtp.port_subscr = bts_base + 2 * conn->rtp.mgcp_rtp_endpoint;
 
 	/* Establish the RTP stream first as looping back to the originator.
 	 * The MDCX will patch through to the counterpart. TODO: play a ring
 	 * tone instead. */
-	msg = mgcp_msg_crcx(mgcp, conn->iu.mgcp_rtp_endpoint, trans->callref,
-			    MGCP_CONN_LOOPBACK);
+	msg = mgcp_msg_crcx(mgcp, conn->rtp.mgcp_rtp_endpoint,
+			    conn->rtp.mgcp_rtp_endpoint, MGCP_CONN_LOOPBACK);
 	return mgcpgw_client_tx(mgcp, msg, mgcp_response_rab_act_cs_crcx, trans);
 }
-#endif
-
-int msc_call_assignment(struct gsm_trans *trans)
-{
-	struct gsm_subscriber_connection *conn = trans->conn;
-
-	switch (conn->via_ran) {
-	case RAN_GERAN_A:
-		LOGP(DMSC, LOGL_ERROR,
-		     "msc_call_assignment(): A-interface BSSMAP Assignment"
-		     " Request not yet implemented\n");
-		return -ENOTSUP;
-
-	case RAN_UTRAN_IU:
-#ifdef BUILD_IU
-		return conn_iu_rab_act_cs(trans);
-#else
-		LOGP(DMSC, LOGL_ERROR,
-		     "msc_call_assignment(): cannot send RAB Activation, built without Iu support\n");
-		return -ENOTSUP;
-#endif
-
-	default:
-		LOGP(DMSC, LOGL_ERROR,
-		     "msc_tx(): conn->via_ran invalid (%d)\n",
-		     conn->via_ran);
-		return -EINVAL;
-	}
-}
 
 static void mgcp_response_bridge_mdcx(struct mgcp_response *r, void *priv);
 
@@ -252,8 +280,8 @@
 	ip = mgcpgw_client_remote_addr_str(mgcp);
 
 	msg = mgcp_msg_mdcx(mgcp,
-			    conn1->iu.mgcp_rtp_endpoint,
-			    ip, conn2->iu.mgcp_rtp_port_cn,
+			    conn1->rtp.mgcp_rtp_endpoint,
+			    ip, conn2->rtp.port_cn,
 			    mode);
 	if (mgcpgw_client_tx(mgcp, msg, mgcp_response_bridge_mdcx, from))
 		LOGP(DMGCP, LOGL_ERROR,
@@ -302,8 +330,58 @@
 	}
 }
 
+int msc_call_connect(struct gsm_trans *trans, uint16_t port, uint32_t ip)
+{
+	/* With this function we inform the MGCP-GW  where (ip/port) it
+	 * has to send its outgoing voic traffic. The receiving end will
+	 * usually be a PBX (e.g. Asterisk). The IP-Address we tell, will
+	 * not only be used to direct the traffic, it will also be used
+	 * as a filter to make sure only RTP packets from the right
+	 * remote end will reach the BSS. This is also the reason why
+	 * inbound audio will not work until this step is performed */
+
+	/* NOTE: This function is used when msc_call_bridge(), is not
+	 * applicable. This is usually the case when an external MNCC
+	 * is in use */
+
+	struct gsm_subscriber_connection *conn;
+	struct mgcpgw_client *mgcp;
+	struct msgb *msg;
+
+	if (!trans)
+		return -EINVAL;
+	if (!trans->conn)
+		return -EINVAL;
+	if (!trans->conn->network)
+		return -EINVAL;
+	if (!trans->conn->network->mgcpgw.client)
+		return -EINVAL;
+
+	mgcp = trans->conn->network->mgcpgw.client;
+
+	struct in_addr ip_addr;
+	ip_addr.s_addr = ntohl(ip);
+
+	conn = trans->conn;
+
+	msg = mgcp_msg_mdcx(mgcp,
+			    conn->rtp.mgcp_rtp_endpoint,
+			    inet_ntoa(ip_addr), port, MGCP_CONN_RECV_SEND);
+	if (mgcpgw_client_tx(mgcp, msg, NULL, trans))
+		LOGP(DMGCP, LOGL_ERROR,
+		     "Failed to send MDCX message for %s\n",
+		     vlr_subscr_name(trans->vsub));
+
+	return 0;
+}
+
 int msc_call_bridge(struct gsm_trans *trans1, struct gsm_trans *trans2)
 {
+	if (!trans1)
+		return -EINVAL;
+	if (!trans2)
+		return -EINVAL;
+
 	/* First setup as loopback and configure the counterparts' endpoints,
 	 * so that when transmission starts the originating addresses are
 	 * already known to be valid. The mgcp callback will continue. */
@@ -314,3 +392,31 @@
 
 	return 0;
 }
+
+void msc_call_release(struct gsm_trans *trans)
+{
+	struct msgb *msg;
+	struct gsm_subscriber_connection *conn;
+	struct mgcpgw_client *mgcp;
+
+	if (!trans)
+		return;
+	if (!trans->conn)
+		return;
+	if (!trans->conn->network)
+		return;
+
+	conn = trans->conn;
+	mgcp = conn->network->mgcpgw.client;
+
+	/* Send DLCX */
+	msg = mgcp_msg_dlcx(mgcp, conn->rtp.mgcp_rtp_endpoint,
+			    conn->rtp.mgcp_rtp_endpoint);
+	if (mgcpgw_client_tx(mgcp, msg, NULL, NULL))
+		LOGP(DMGCP, LOGL_ERROR,
+		     "Failed to send DLCX message for %s\n",
+		     vlr_subscr_name(trans->vsub));
+
+	/* Release endpoint id */
+	mgcpgw_client_release_endpoint(conn->rtp.mgcp_rtp_endpoint, mgcp);
+}
diff --git a/src/libmsc/msc_vty.c b/src/libmsc/msc_vty.c
index 82dc7d6..01e7e82 100644
--- a/src/libmsc/msc_vty.c
+++ b/src/libmsc/msc_vty.c
@@ -64,6 +64,26 @@
 	return CMD_SUCCESS;
 }
 
+DEFUN(cfg_msc_cs7_instance_a,
+      cfg_msc_cs7_instance_a_cmd,
+      "cs7-instance-a <0-15>",
+      "Set SS7 to be used by the A-Interface.\n" "SS7 instance reference number\n")
+{
+	struct gsm_network *gsmnet = gsmnet_from_vty(vty);
+	gsmnet->a.cs7_instance = atoi(argv[0]);
+	return CMD_SUCCESS;
+}
+
+DEFUN(cfg_msc_cs7_instance_iu,
+      cfg_msc_cs7_instance_iu_cmd,
+      "cs7-instance-iu <0-15>",
+      "Set SS7 to be used by the Iu-Interface.\n" "SS7 instance reference number\n")
+{
+	struct gsm_network *gsmnet = gsmnet_from_vty(vty);
+	gsmnet->iu.cs7_instance = atoi(argv[0]);
+	return CMD_SUCCESS;
+}
+
 static int config_write_msc(struct vty *vty)
 {
 	struct gsm_network *gsmnet = gsmnet_from_vty(vty);
@@ -72,6 +92,11 @@
 	vty_out(vty, " %sassign-tmsi%s",
 		gsmnet->vlr->cfg.assign_tmsi? "" : "no ", VTY_NEWLINE);
 
+	vty_out(vty, " cs7-instance-a %u%s", gsmnet->a.cs7_instance,
+		VTY_NEWLINE);
+	vty_out(vty, " cs7-instance-iu %u%s", gsmnet->iu.cs7_instance,
+		VTY_NEWLINE);
+
 	mgcpgw_client_config_write(vty, " ");
 #ifdef BUILD_IU
 	iu_vty_config_write(vty, " ");
@@ -123,6 +148,9 @@
 	vty_install_default(MSC_NODE);
 	install_element(MSC_NODE, &cfg_msc_assign_tmsi_cmd);
 	install_element(MSC_NODE, &cfg_msc_no_assign_tmsi_cmd);
+	install_element(MSC_NODE, &cfg_msc_cs7_instance_a_cmd);
+	install_element(MSC_NODE, &cfg_msc_cs7_instance_iu_cmd);
+
 	mgcpgw_client_vty_init(MSC_NODE, &msc_network->mgcpgw.conf);
 #ifdef BUILD_IU
 	iu_vty_init(MSC_NODE, &msc_network->iu.rab_assign_addr_enc);
diff --git a/src/libmsc/osmo_msc.c b/src/libmsc/osmo_msc.c
index ddc3836..866cfbd 100644
--- a/src/libmsc/osmo_msc.c
+++ b/src/libmsc/osmo_msc.c
@@ -29,11 +29,12 @@
 #include <openbsc/vlr.h>
 #include <openbsc/osmo_msc.h>
 #include <openbsc/iu.h>
+#include <openbsc/a_iface.h>
 
 #include <openbsc/gsm_04_11.h>
 
 /* Receive a SAPI-N-REJECT from BSC */
-static void msc_sapi_n_reject(struct gsm_subscriber_connection *conn, int dlci)
+void msc_sapi_n_reject(struct gsm_subscriber_connection *conn, int dlci)
 {
 	int sapi = dlci & 0x7;
 
@@ -106,24 +107,24 @@
 }
 
 /* Receive an ASSIGNMENT COMPLETE from BSC */
-static void msc_assign_compl(struct gsm_subscriber_connection *conn,
-			     uint8_t rr_cause, uint8_t chosen_channel,
-			     uint8_t encr_alg_id, uint8_t speec)
+void msc_assign_compl(struct gsm_subscriber_connection *conn,
+		      uint8_t rr_cause, uint8_t chosen_channel,
+		      uint8_t encr_alg_id, uint8_t speec)
 {
 	LOGP(DRR, LOGL_DEBUG, "MSC assign complete (do nothing).\n");
 }
 
 /* Receive an ASSIGNMENT FAILURE from BSC */
-static void msc_assign_fail(struct gsm_subscriber_connection *conn,
-			    uint8_t cause, uint8_t *rr_cause)
+void msc_assign_fail(struct gsm_subscriber_connection *conn,
+		     uint8_t cause, uint8_t *rr_cause)
 {
 	LOGP(DRR, LOGL_DEBUG, "MSC assign failure (do nothing).\n");
 }
 
 /* Receive a CLASSMARK CHANGE from BSC */
-static void msc_classmark_chg(struct gsm_subscriber_connection *conn,
-			      const uint8_t *cm2, uint8_t cm2_len,
-			      const uint8_t *cm3, uint8_t cm3_len)
+void msc_classmark_chg(struct gsm_subscriber_connection *conn,
+		       const uint8_t *cm2, uint8_t cm2_len,
+		       const uint8_t *cm3, uint8_t cm3_len)
 {
 	if (cm2 && cm2_len) {
 		if (cm2_len > sizeof(conn->classmark.classmark2)) {
@@ -250,7 +251,7 @@
 }
 
 /* Receive a CLEAR REQUEST from BSC */
-static int msc_clear_request(struct gsm_subscriber_connection *conn, uint32_t cause)
+int msc_clear_request(struct gsm_subscriber_connection *conn, uint32_t cause)
 {
 	msc_subscr_conn_close(conn, cause);
 	return 1;
@@ -290,7 +291,7 @@
 		 * says "unknown UE" for each release outcome. */
 		break;
 	case RAN_GERAN_A:
-		/* future: a_iface_tx_clear_cmd(conn); */
+		a_iface_tx_clear_cmd(conn);
 		break;
 	default:
 		LOGP(DMM, LOGL_ERROR, "%s: Unknown RAN type, cannot tx release/clear\n",
diff --git a/src/libmsc/subscr_conn.c b/src/libmsc/subscr_conn.c
index 31decc7..cdeeae9 100644
--- a/src/libmsc/subscr_conn.c
+++ b/src/libmsc/subscr_conn.c
@@ -31,6 +31,8 @@
 #include <openbsc/transaction.h>
 #include <openbsc/signal.h>
 #include <openbsc/iu.h>
+#include <openbsc/a_iface.h>
+
 
 #define SUBSCR_CONN_TIMEOUT 5 /* seconds */
 
@@ -223,7 +225,6 @@
 
 	if (!conn)
 		return;
-
 	conn->conn_fsm = NULL;
  	msc_subscr_conn_close(conn, cause);
 	msc_subscr_conn_put(conn);
diff --git a/src/osmo-bsc/Makefile.am b/src/osmo-bsc/Makefile.am
index ae9410c..5642fb2 100644
--- a/src/osmo-bsc/Makefile.am
+++ b/src/osmo-bsc/Makefile.am
@@ -14,6 +14,7 @@
 	$(LIBOSMOSCCP_CFLAGS) \
 	$(COVERAGE_CFLAGS) \
 	$(LIBOSMOABIS_CFLAGS) \
+	$(LIBOSMOSIGTRAN_CFLAGS) \
 	$(NULL)
 
 AM_LDFLAGS = \
@@ -30,7 +31,7 @@
 	osmo_bsc_api.c \
 	osmo_bsc_grace.c \
 	osmo_bsc_msc.c \
-	osmo_bsc_sccp.c \
+	osmo_bsc_sigtran.c \
 	osmo_bsc_filter.c \
 	osmo_bsc_bssap.c \
 	osmo_bsc_audio.c \
@@ -52,4 +53,5 @@
 	$(LIBOSMOCTRL_LIBS) \
 	$(COVERAGE_LDFLAGS) \
 	$(LIBOSMOABIS_LIBS) \
+	$(LIBOSMOSIGTRAN_LIBS) \
 	$(NULL)
diff --git a/src/osmo-bsc/osmo_bsc_api.c b/src/osmo-bsc/osmo_bsc_api.c
index 8c33e2b..f7343f7 100644
--- a/src/osmo-bsc/osmo_bsc_api.c
+++ b/src/osmo-bsc/osmo_bsc_api.c
@@ -27,6 +27,7 @@
 #include <osmocom/gsm/gsm0808.h>
 
 #include <osmocom/sccp/sccp.h>
+#include <openbsc/osmo_bsc_sigtran.h>
 
 #define return_when_not_connected(conn) \
 	if (!conn->sccp_con) {\
@@ -45,7 +46,7 @@
 		LOGP(DMSC, LOGL_ERROR, "Failed to allocate response.\n"); \
 		return; \
 	} \
-	bsc_queue_for_msc(conn->sccp_con, resp);
+	osmo_bsc_sigtran_send(conn->sccp_con, resp);
 
 static int bsc_clear_request(struct gsm_subscriber_connection *conn, uint32_t cause);
 static int complete_layer3(struct gsm_subscriber_connection *conn,
@@ -263,7 +264,8 @@
 	}
 
 	/* allocate resource for a new connection */
-	ret = bsc_create_new_connection(conn, msc, send_ping);
+	//ret = bsc_create_new_connection(conn, msc, send_ping);
+	ret = osmo_bsc_sigtran_new_conn(conn, msc);
 
 	if (ret != BSC_CON_SUCCESS) {
 		/* allocation has failed */
@@ -292,13 +294,13 @@
 	if (!resp) {
 		LOGP(DMSC, LOGL_DEBUG, "Failed to create layer3 message.\n");
 		sccp_connection_free(conn->sccp_con->sccp);
-		bsc_delete_connection(conn->sccp_con);
+		osmo_bsc_sigtran_del_conn(conn->sccp_con);
 		return BSC_API_CONN_POL_REJECT;
 	}
 
-	if (bsc_open_connection(conn->sccp_con, resp) != 0) {
+	if (osmo_bsc_sigtran_open_conn(conn->sccp_con, resp) != 0) {
 		sccp_connection_free(conn->sccp_con->sccp);
-		bsc_delete_connection(conn->sccp_con);
+		osmo_bsc_sigtran_del_conn(conn->sccp_con);
 		msgb_free(resp);
 		return BSC_API_CONN_POL_REJECT;
 	}
@@ -433,11 +435,28 @@
 	struct msgb *resp;
 	return_when_not_connected(conn);
 
-	LOGP(DMSC, LOGL_INFO, "Tx MSC ASSIGN COMPL\n");
+	if (is_ipaccess_bts(conn->bts) && conn->sccp_con->rtp_ip) {
+		/* NOTE: In a network that makes use of an IPA base station
+		 * and AoIP, we have to wait until the BTS reports its RTP
+		 * IP/Port combination back to BSC via RSL. Unfortunately, the
+		 * IPA protocol sends its Abis assignment complete message
+		 * before it sends its RTP IP/Port via IPACC. So we will now
+		 * postpone the AoIP assignment completed message until we
+		 * know the RTP IP/Port combination. */
+		LOGP(DMSC, LOGL_INFO, "POSTPONE MSC ASSIGN COMPL\n");
+		conn->lchan->abis_ip.ass_compl.rr_cause = rr_cause;
+		conn->lchan->abis_ip.ass_compl.chosen_channel = chosen_channel;
+		conn->lchan->abis_ip.ass_compl.encr_alg_id = encr_alg_id;
+		conn->lchan->abis_ip.ass_compl.speech_mode = speech_model;
+		conn->lchan->abis_ip.ass_compl.valid = true;
 
-	resp = gsm0808_create_assignment_completed(rr_cause, chosen_channel,
-						   encr_alg_id, speech_model);
-	queue_msg_or_return(resp);
+	} else {
+		/* NOTE: Send the A assignment complete message immediately. */
+		LOGP(DMSC, LOGL_INFO, "Tx MSC ASSIGN COMPL\n");
+		resp = gsm0808_create_assignment_completed(rr_cause, chosen_channel,
+							   encr_alg_id, speech_model);
+		queue_msg_or_return(resp);
+	}
 }
 
 static void bsc_assign_fail(struct gsm_subscriber_connection *conn,
@@ -474,7 +493,7 @@
 		return 1;
 	}
 
-	bsc_queue_for_msc(sccp, resp);
+	osmo_bsc_sigtran_send(sccp, resp);
 	return 1;
 }
 
diff --git a/src/osmo-bsc/osmo_bsc_audio.c b/src/osmo-bsc/osmo_bsc_audio.c
index 1160209..b4ffa88 100644
--- a/src/osmo-bsc/osmo_bsc_audio.c
+++ b/src/osmo-bsc/osmo_bsc_audio.c
@@ -26,15 +26,57 @@
 #include <openbsc/gsm_data.h>
 #include <openbsc/debug.h>
 #include <openbsc/signal.h>
+#include <osmocom/gsm/gsm0808.h>
+#include <osmocom/gsm/gsm0808_utils.h>
+#include <openbsc/osmo_bsc_sigtran.h>
 
 #include <arpa/inet.h>
 
+/* Generate and send assignment complete message */
+static int send_aoip_ass_compl(struct gsm_subscriber_connection *conn, struct gsm_lchan *lchan)
+{
+	struct msgb *resp;
+	struct sockaddr_storage rtp_addr;
+	struct sockaddr_in rtp_addr_in;
+	struct gsm0808_speech_codec sc;
+
+	OSMO_ASSERT(lchan->abis_ip.ass_compl.valid == true);
+
+	/* Package RTP-Address data */
+	memset(&rtp_addr_in, 0, sizeof(rtp_addr_in));
+	rtp_addr_in.sin_family = AF_INET;
+	rtp_addr_in.sin_port = htons(lchan->abis_ip.bound_port);
+	rtp_addr_in.sin_addr.s_addr = htonl(lchan->abis_ip.bound_ip);
+	memset(&rtp_addr, 0, sizeof(rtp_addr));
+	memcpy(&rtp_addr, &rtp_addr_in, sizeof(rtp_addr_in));
+
+	/* Extrapolate speech codec from speech mode */
+	gsm0808_speech_codec_from_chan_type(&sc, lchan->abis_ip.ass_compl.speech_mode);
+
+	/* Generate message */
+	resp = gsm0808_create_ass_compl(lchan->abis_ip.ass_compl.rr_cause,
+					lchan->abis_ip.ass_compl.chosen_channel,
+					lchan->abis_ip.ass_compl.encr_alg_id,
+					lchan->abis_ip.ass_compl.speech_mode,
+					&rtp_addr,
+					&sc,
+					NULL);
+
+	if (!resp) {
+		LOGP(DMSC, LOGL_ERROR, "Failed to generate assignment completed message!\n"); \
+		return -EINVAL;
+	}
+
+	return osmo_bsc_sigtran_send(conn->sccp_con, resp);
+}
+
 static int handle_abisip_signal(unsigned int subsys, unsigned int signal,
 				 void *handler_data, void *signal_data)
 {
 	struct gsm_subscriber_connection *con;
 	struct gsm_lchan *lchan = signal_data;
 	int rc;
+	uint32_t rtp_ip;
 
 	if (subsys != SS_ABISIP)
 		return 0;
@@ -49,11 +91,19 @@
 		 * TODO: handle handover here... then the audio should go to
 		 * the old mgcp port..
 		 */
+
 		/* we can ask it to connect now */
 		LOGP(DMSC, LOGL_DEBUG, "Connecting BTS to port: %d conn: %d\n",
 		     con->sccp_con->rtp_port, lchan->abis_ip.conn_id);
 
-		rc = rsl_ipacc_mdcx(lchan, ntohl(INADDR_ANY),
+		/* If AoIP is in use, the rtp_ip, which has been communicated
+		 * via the A interface as connect_ip */
+		if(con->sccp_con->rtp_ip)
+			rtp_ip = con->sccp_con->rtp_ip;
+		else
+			rtp_ip = ntohl(INADDR_ANY);
+
+		rc = rsl_ipacc_mdcx(lchan, rtp_ip,
 				    con->sccp_con->rtp_port,
 				    lchan->abis_ip.rtp_payload2);
 		if (rc < 0) {
@@ -61,6 +111,24 @@
 			return rc;
 		}
 		break;
+
+	case S_ABISIP_MDCX_ACK:
+		if (con->ho_lchan) {
+			/* NOTE: When an ho_lchan exists, the MDCX is part of an
+			 * handover operation (intra-bsc). This means we will not
+			 * inform the MSC about the event, which means that no
+			 * assignment complete message is transmitted */
+			LOGP(DMSC, LOGL_INFO," RTP connection handover complete\n");
+		} else if (is_ipaccess_bts(con->bts) && con->sccp_con->rtp_ip) {
+			/* NOTE: This is only relevant on AoIP networks with
+			 * IPA based base stations. See also osmo_bsc_api.c,
+			 * function bsc_assign_compl() */
+			LOGP(DMSC, LOGL_INFO, "Tx MSC ASSIGN COMPL (POSTPONED)\n");
+			if (send_aoip_ass_compl(con, lchan) != 0)
+				return -EINVAL;
+		}
+		break;
+	break;
 	}
 
 	return 0;
diff --git a/src/osmo-bsc/osmo_bsc_bssap.c b/src/osmo-bsc/osmo_bsc_bssap.c
index 100f664..4353b9a 100644
--- a/src/osmo-bsc/osmo_bsc_bssap.c
+++ b/src/osmo-bsc/osmo_bsc_bssap.c
@@ -29,11 +29,21 @@
 
 #include <osmocom/gsm/protocol/gsm_08_08.h>
 #include <osmocom/gsm/gsm0808.h>
+#include <osmocom/gsm/gsm0808_utils.h>
+#include <openbsc/osmo_bsc_sigtran.h>
+#include <openbsc/a_reset.h>
+#include <osmocom/core/byteswap.h>
+
+#define IP_V4_ADDR_LEN 4
 
 /*
  * helpers for the assignment command
  */
-enum gsm0808_permitted_speech audio_support_to_gsm88(struct gsm_audio_support *audio)
+
+/* Helper function for match_codec_pref(), looks up a matching permitted speech
+ * value for a given msc audio codec pref */
+enum gsm0808_permitted_speech audio_support_to_gsm88(struct gsm_audio_support
+						     *audio)
 {
 	if (audio->hr) {
 		switch (audio->ver) {
@@ -47,8 +57,9 @@
 			return GSM0808_PERM_HR3;
 			break;
 		default:
-			    LOGP(DMSC, LOGL_ERROR, "Wrong speech mode: %d\n", audio->ver);
-			    return GSM0808_PERM_FR1;
+			LOGP(DMSC, LOGL_ERROR, "Wrong speech mode: %d\n",
+			     audio->ver);
+			return GSM0808_PERM_FR1;
 		}
 	} else {
 		switch (audio->ver) {
@@ -62,12 +73,15 @@
 			return GSM0808_PERM_FR3;
 			break;
 		default:
-			LOGP(DMSC, LOGL_ERROR, "Wrong speech mode: %d\n", audio->ver);
+			LOGP(DMSC, LOGL_ERROR, "Wrong speech mode: %d\n",
+			     audio->ver);
 			return GSM0808_PERM_HR1;
 		}
 	}
 }
 
+/* Helper function for match_codec_pref(), looks up a matching chan mode for
+ * a given permitted speech value */
 enum gsm48_chan_mode gsm88_to_chan_mode(enum gsm0808_permitted_speech speech)
 {
 	switch (speech) {
@@ -83,16 +97,130 @@
 	case GSM0808_PERM_FR3:
 		return GSM48_CMODE_SPEECH_AMR;
 		break;
+	default:
+		LOGP(DMSC, LOGL_FATAL,
+		     "Unsupported permitted speech selected, assuming AMR as channel mode...\n");
+		return GSM48_CMODE_SPEECH_AMR;
+	}
+}
+
+/* Helper function for match_codec_pref(), tests if a given audio support
+ * matches one of the permitted speech settings of the channel type element.
+ * The matched permitted speech value is then also compared against the
+ * speech codec list. (optional, only relevant for AoIP) */
+static bool test_codec_pref(const struct gsm0808_channel_type *ct,
+			    const struct gsm0808_speech_codec_list *scl,
+			    uint8_t perm_spch)
+{
+	unsigned int i;
+	bool match = false;
+	struct gsm0808_speech_codec sc;
+	int rc;
+
+	/* Try to finde the given permitted speech value in the
+	 * codec list of the channel type element */
+	for (i = 0; i < ct->perm_spch_len; i++) {
+		if (ct->perm_spch[i] == perm_spch) {
+			match = true;
+			break;
+		}
 	}
 
-	LOGP(DMSC, LOGL_FATAL, "Should not be reached.\n");
-	return GSM48_CMODE_SPEECH_AMR;
+	/* If we do not have a speech codec list to test against,
+	 * we just exit early (will be always the case in non-AoIP networks) */
+	if (!scl)
+		return match;
+
+	/* If we failed to match until here, there is no
+	 * point in testing further */
+	if (match == false)
+		return false;
+
+	/* Extrapolate speech codec data */
+	rc = gsm0808_speech_codec_from_chan_type(&sc, perm_spch);
+	if (rc < 0)
+		return false;
+
+	/* Try to find extrapolated speech codec data in
+	 * the speech codec list */
+	for (i = 0; i < scl->len; i++) {
+		if (memcmp(&sc, &scl->codec[i], sizeof(sc)) == 0)
+			return true;
+	}
+
+	return false;
+}
+
+/* Helper function for bssmap_handle_assignm_req(), matches the codec
+ * preferences from the MSC with the codec preferences */
+static int match_codec_pref(int *full_rate, enum gsm48_chan_mode *chan_mode,
+			    const struct gsm0808_channel_type *ct,
+			    const struct gsm0808_speech_codec_list *scl,
+			    const struct bsc_msc_data *msc)
+{
+	unsigned int i;
+	uint8_t perm_spch;
+	bool match = false;
+
+	for (i = 0; i < msc->audio_length; i++) {
+		perm_spch = audio_support_to_gsm88(msc->audio_support[i]);
+		if (test_codec_pref(ct, scl, perm_spch)) {
+			match = true;
+			break;
+		}
+	}
+
+	/* Exit without result, in case no match can be deteched */
+	if (!match) {
+		*full_rate = -1;
+		*chan_mode = GSM48_CMODE_SIGN;
+		return -1;
+	}
+
+	/* Check if the result is a half or full rate codec */
+	if (perm_spch == GSM0808_PERM_HR1 || perm_spch == GSM0808_PERM_HR2
+	    || perm_spch == GSM0808_PERM_HR3 || perm_spch == GSM0808_PERM_HR4
+	    || perm_spch == GSM0808_PERM_HR6)
+		*full_rate = 0;
+	else
+		*full_rate = 1;
+
+	/* Lookup a channel mode for the selected codec */
+	*chan_mode = gsm88_to_chan_mode(perm_spch);
+
+	return 0;
 }
 
 static int bssmap_handle_reset_ack(struct bsc_msc_data *msc,
 				   struct msgb *msg, unsigned int length)
 {
-	LOGP(DMSC, LOGL_NOTICE, "Reset ACK from MSC\n");
+	LOGP(DMSC, LOGL_NOTICE, "RESET ACK from MSC: %s\n",
+	     osmo_sccp_addr_name(osmo_ss7_instance_find(msc->a.cs7_instance),
+				 &msc->a.msc_addr));
+
+	/* Inform the FSM that controls the RESET/RESET-ACK procedure
+	 * that we have successfully received the reset-ack message */
+	a_reset_ack_confirm(msc->a.reset);
+
+	return 0;
+}
+
+/* Handle MSC sided reset */
+static int bssmap_handle_reset(struct bsc_msc_data *msc,
+			       struct msgb *msg, unsigned int length)
+{
+	LOGP(DMSC, LOGL_NOTICE, "RESET from MSC: %s\n",
+	     osmo_sccp_addr_name(osmo_ss7_instance_find(msc->a.cs7_instance),
+				 &msc->a.msc_addr));
+
+	/* Instruct the bsc to close all open sigtran connections and to
+	 * close all active channels on the BTS side as well */
+	osmo_bsc_sigtran_reset(msc);
+
+	/* Inform the MSC that we have received the reset request and
+	 * that we acted accordingly */
+	osmo_bsc_sigtran_tx_reset_ack(msc);
+
 	return 0;
 }
 
@@ -199,7 +327,7 @@
 		return -1;
 	}
 
-	bsc_queue_for_msc(conn, resp);
+	osmo_bsc_sigtran_send(conn, resp);
 	return 0;
 }
 
@@ -276,7 +404,7 @@
 		return -1;
 	}
 
-	bsc_queue_for_msc(conn, resp);
+	osmo_bsc_sigtran_send(conn, resp);
 	return -1;
 }
 
@@ -291,99 +419,141 @@
 	struct msgb *resp;
 	struct bsc_msc_data *msc;
 	struct tlv_parsed tp;
-	uint8_t *data;
-	uint8_t timeslot;
-	uint8_t multiplex;
+	uint8_t timeslot = 0;
+	uint8_t multiplex = 0;
 	enum gsm48_chan_mode chan_mode = GSM48_CMODE_SIGN;
-	int i, supported, port, full_rate = -1;
+	int port, full_rate = -1;
+	bool aoip = false;
+	struct sockaddr_storage rtp_addr;
+	struct sockaddr_in *rtp_addr_in;
+	struct gsm0808_channel_type ct;
+	struct gsm0808_speech_codec_list scl;
+	struct gsm0808_speech_codec_list *scl_ptr = NULL;
+	int rc;
+	const uint8_t *data;
+	char len;
 
 	if (!conn->conn) {
-		LOGP(DMSC, LOGL_ERROR, "No lchan/msc_data in cipher mode command.\n");
+		LOGP(DMSC, LOGL_ERROR,
+		     "No lchan/msc_data in cipher mode command.\n");
 		return -1;
 	}
 
+	msc = conn->msc;
+
 	tlv_parse(&tp, gsm0808_att_tlvdef(), msg->l4h + 1, length - 1, 0, 0);
 
+	/* Check for channel type element, if its missing, immediately reject */
 	if (!TLVP_PRESENT(&tp, GSM0808_IE_CHANNEL_TYPE)) {
 		LOGP(DMSC, LOGL_ERROR, "Mandatory channel type not present.\n");
 		goto reject;
 	}
 
-	if (!TLVP_PRESENT(&tp, GSM0808_IE_CIRCUIT_IDENTITY_CODE)) {
-		LOGP(DMSC, LOGL_ERROR, "Identity code missing. Audio routing will not work.\n");
-		goto reject;
-	}
-
-	conn->cic = osmo_load16be(TLVP_VAL(&tp, GSM0808_IE_CIRCUIT_IDENTITY_CODE));
-	timeslot = conn->cic & 0x1f;
-	multiplex = (conn->cic & ~0x1f) >> 5;
-
-	/*
-	 * Currently we only support a limited subset of all
-	 * possible channel types. The limitation ends by not using
-	 * multi-slot, limiting the channel coding, speech...
-	 */
-	if (TLVP_LEN(&tp, GSM0808_IE_CHANNEL_TYPE) < 3) {
-		LOGP(DMSC, LOGL_ERROR, "ChannelType len !=3 not supported: %d\n",
-			TLVP_LEN(&tp, GSM0808_IE_CHANNEL_TYPE));
-		goto reject;
-	}
-
-	/*
-	 * Try to figure out if we support the proposed speech codecs. For
-	 * now we will always pick the full rate codecs.
-	 */
-
-	data = (uint8_t *) TLVP_VAL(&tp, GSM0808_IE_CHANNEL_TYPE);
-	if ((data[0] & 0xf) != 0x1) {
-		LOGP(DMSC, LOGL_ERROR, "ChannelType != speech: %d\n", data[0]);
-		goto reject;
-	}
-
-	/*
-	 * go through the list of preferred codecs of our gsm network
-	 * and try to find it among the permitted codecs. If we found
-	 * it we will send chan_mode to the right mode and break the
-	 * inner loop. The outer loop will exit due chan_mode having
-	 * the correct value.
-	 */
-	full_rate = 0;
-	msc = conn->msc;
-	for (supported = 0;
-		chan_mode == GSM48_CMODE_SIGN && supported < msc->audio_length;
-		++supported) {
-
-		int perm_val = audio_support_to_gsm88(msc->audio_support[supported]);
-		for (i = 2; i < TLVP_LEN(&tp, GSM0808_IE_CHANNEL_TYPE); ++i) {
-			if ((data[i] & 0x7f) == perm_val) {
-				chan_mode = gsm88_to_chan_mode(perm_val);
-				full_rate = (data[i] & 0x4) == 0;
-				break;
-			} else if ((data[i] & 0x80) == 0x00) {
-				break;
-			}
+	/* Detect if a CIC code is present, if so, we use the classic ip.access
+	 * method to calculate the RTP port */
+	if (TLVP_PRESENT(&tp, GSM0808_IE_CIRCUIT_IDENTITY_CODE)) {
+		conn->cic =
+		    osmo_load16be(TLVP_VAL
+				  (&tp, GSM0808_IE_CIRCUIT_IDENTITY_CODE));
+		timeslot = conn->cic & 0x1f;
+		multiplex = (conn->cic & ~0x1f) >> 5;
+	} else if (TLVP_PRESENT(&tp, GSM0808_IE_AOIP_TRASP_ADDR)) {
+		/* Decode AoIP transport address element */
+		data = TLVP_VAL(&tp, GSM0808_IE_AOIP_TRASP_ADDR);
+		len = TLVP_LEN(&tp, GSM0808_IE_AOIP_TRASP_ADDR);
+		rc = gsm0808_dec_aoip_trasp_addr(&rtp_addr, data, len);
+		if (rc < 0) {
+			LOGP(DMSC, LOGL_ERROR,
+			     "Unable to decode aoip transport address.\n");
+			goto reject;
 		}
+		aoip = true;
+	} else {
+		LOGP(DMSC, LOGL_ERROR,
+		     "transport address missing. Audio routing will not work.\n");
+		goto reject;
 	}
 
-	if (chan_mode == GSM48_CMODE_SIGN) {
+	/* Decode speech codec list (AoIP) */
+	if (aoip) {
+		/* Check for speech codec list element */
+		if (!TLVP_PRESENT(&tp, GSM0808_IE_SPEECH_CODEC_LIST)) {
+			LOGP(DMSC, LOGL_ERROR,
+			     "Mandatory speech codec list not present.\n");
+			goto reject;
+		}
+
+		/* Decode Speech Codec list */
+		data = TLVP_VAL(&tp, GSM0808_IE_SPEECH_CODEC_LIST);
+		len = TLVP_LEN(&tp, GSM0808_IE_SPEECH_CODEC_LIST);
+		rc = gsm0808_dec_speech_codec_list(&scl, data, len);
+		if (rc < 0) {
+			LOGP(DMSC, LOGL_ERROR,
+			     "Unable to decode speech codec list\n");
+			goto reject;
+		}
+		scl_ptr = &scl;
+	}
+
+	/* Decode Channel Type element */
+	data = TLVP_VAL(&tp, GSM0808_IE_CHANNEL_TYPE);
+	len = TLVP_LEN(&tp, GSM0808_IE_CHANNEL_TYPE);
+	rc = gsm0808_dec_channel_type(&ct, data, len);
+	if (rc < 0) {
+		LOGP(DMSC, LOGL_ERROR, "unable to decode channel type.\n");
+		goto reject;
+	}
+
+	/* Currently we only support a limited subset of all
+	 * possible channel types. The limitation ends by not using
+	 * multi-slot, limiting the channel coding to speech */
+	if (ct.ch_indctr != GSM0808_CHAN_SPEECH) {
+		LOGP(DMSC, LOGL_ERROR,
+		     "Unsupported channel type, currently only speech is supported!\n");
+		goto reject;
+	}
+
+	/* Match codec information from the assignment command against the
+	 * local preferences of the BSC */
+	rc = match_codec_pref(&full_rate, &chan_mode, &ct, scl_ptr, msc);
+	if (rc < 0) {
 		LOGP(DMSC, LOGL_ERROR, "No supported audio type found.\n");
 		goto reject;
 	}
 
-	/* map it to a MGCP Endpoint and a RTP port */
-	port = mgcp_timeslot_to_endpoint(multiplex, timeslot);
-	conn->rtp_port = rtp_calculate_port(port, msc->rtp_base);
+	if (aoip == false) {
+		/* map it to a MGCP Endpoint and a RTP port */
+		port = mgcp_timeslot_to_endpoint(multiplex, timeslot);
+		conn->rtp_port = rtp_calculate_port(port, msc->rtp_base);
+		conn->rtp_ip = 0;
+	} else {
+		/* use address / port supplied with the AoIP
+		 * transport address element */
+		if (rtp_addr.ss_family == AF_INET) {
+			rtp_addr_in = (struct sockaddr_in *)&rtp_addr;
+			conn->rtp_port = osmo_ntohs(rtp_addr_in->sin_port);
+			memcpy(&conn->rtp_ip, &rtp_addr_in->sin_addr.s_addr,
+			       IP_V4_ADDR_LEN);
+			conn->rtp_ip = osmo_ntohl(conn->rtp_ip);
+		} else {
+			LOGP(DMSC, LOGL_ERROR,
+			     "Unsopported addressing scheme. (supports only IPV4)\n");
+			goto reject;
+		}
+	}
 
 	return gsm0808_assign_req(conn->conn, chan_mode, full_rate);
 
 reject:
-	resp = gsm0808_create_assignment_failure(GSM0808_CAUSE_NO_RADIO_RESOURCE_AVAILABLE, NULL);
+	resp =
+	    gsm0808_create_assignment_failure
+	    (GSM0808_CAUSE_NO_RADIO_RESOURCE_AVAILABLE, NULL);
 	if (!resp) {
 		LOGP(DMSC, LOGL_ERROR, "Channel allocation failure.\n");
 		return -1;
 	}
 
-	bsc_queue_for_msc(conn, resp);
+	osmo_bsc_sigtran_send(conn, resp);
 	return -1;
 }
 
@@ -404,6 +574,9 @@
 	case BSS_MAP_MSG_RESET_ACKNOWLEDGE:
 		ret = bssmap_handle_reset_ack(msc, msg, length);
 		break;
+	case BSS_MAP_MSG_RESET:
+		ret = bssmap_handle_reset(msc, msg, length);
+		break;
 	case BSS_MAP_MSG_PAGING:
 		ret = bssmap_handle_paging(msc, msg, length);
 		break;
@@ -524,8 +697,8 @@
 	return 0;
 }
 
-int bsc_handle_dt1(struct osmo_bsc_sccp_con *conn,
-		   struct msgb *msg, unsigned int len)
+int bsc_handle_dt(struct osmo_bsc_sccp_con *conn,
+		  struct msgb *msg, unsigned int len)
 {
 	if (len < sizeof(struct bssmap_header)) {
 		LOGP(DMSC, LOGL_ERROR, "The header is too short.\n");
diff --git a/src/osmo-bsc/osmo_bsc_main.c b/src/osmo-bsc/osmo_bsc_main.c
index 90651b9..cf188a9 100644
--- a/src/osmo-bsc/osmo_bsc_main.c
+++ b/src/osmo-bsc/osmo_bsc_main.c
@@ -28,6 +28,7 @@
 #include <openbsc/vty.h>
 #include <openbsc/ipaccess.h>
 #include <openbsc/ctrl.h>
+#include <openbsc/osmo_bsc_sigtran.h>
 
 #include <osmocom/ctrl/control_cmd.h>
 #include <osmocom/ctrl/control_if.h>
@@ -217,6 +218,10 @@
 	bsc_msg_lst_vty_init(tall_bsc_ctx, &access_lists, BSC_NODE);
 	ctrl_vty_init(tall_bsc_ctx);
 
+	/* Initalize SS7 */
+	osmo_ss7_init();
+	osmo_ss7_vty_init_asp(tall_bsc_ctx);
+
 	INIT_LLIST_HEAD(&access_lists);
 
 	/* parse options */
@@ -269,9 +274,8 @@
 		}
 	}
 
-
-	if (osmo_bsc_sccp_init(bsc_gsmnet) != 0) {
-		LOGP(DNM, LOGL_ERROR, "Failed to register SCCP.\n");
+	if (osmo_bsc_sigtran_init(&bsc_gsmnet->bsc_data->mscs) != 0) {
+		LOGP(DNM, LOGL_ERROR, "Failed to initalize sigtran backhaul.\n");
 		exit(1);
 	}
 
diff --git a/src/osmo-bsc/osmo_bsc_msc.c b/src/osmo-bsc/osmo_bsc_msc.c
index 8d02624..351fd2c 100644
--- a/src/osmo-bsc/osmo_bsc_msc.c
+++ b/src/osmo-bsc/osmo_bsc_msc.c
@@ -42,7 +42,7 @@
 #include <netinet/tcp.h>
 #include <unistd.h>
 
-
+#if 0
 static void initialize_if_needed(struct bsc_msc_connection *conn);
 static void send_lacs(struct gsm_network *net, struct bsc_msc_connection *conn);
 static void send_id_get_response(struct bsc_msc_data *data, int fd, struct msgb *inp);
@@ -52,6 +52,8 @@
 /*
  * MGCP forwarding code
  */
+
+#endif
 static int mgcp_do_read(struct osmo_fd *fd)
 {
 	struct bsc_msc_data *data = (struct bsc_msc_data *) fd->data;
@@ -93,6 +95,7 @@
 	return ret;
 }
 
+#if 0
 static void mgcp_forward(struct bsc_msc_data *data, struct msgb *msg)
 {
 	struct msgb *mgcp;
@@ -115,6 +118,7 @@
 		msgb_free(mgcp);
 	}
 }
+#endif
 
 static int mgcp_create_port(struct bsc_msc_data *data)
 {
@@ -168,6 +172,7 @@
 	return 0;
 }
 
+
 /*
  * Send data to the network
  */
@@ -183,6 +188,7 @@
 	return 0;
 }
 
+#if 0
 int msc_queue_write_with_ping(struct bsc_msc_connection *conn,
 			struct msgb *msg, int proto)
 {
@@ -356,10 +362,10 @@
 
 static void msc_pong_timeout_cb(void *_data)
 {
-	struct bsc_msc_data *data = (struct bsc_msc_data *) _data;
+//	struct bsc_msc_data *data = (struct bsc_msc_data *) _data;
 
 	LOGP(DMSC, LOGL_ERROR, "MSC didn't answer PING. Closing connection.\n");
-	bsc_msc_lost(data->msc_con);
+//	bsc_msc_lost(data->msc_con);
 }
 
 static void msc_connection_connected(struct bsc_msc_connection *con)
@@ -368,12 +374,12 @@
 	struct bsc_msc_data *data;
 	int ret, on;
 	on = 1;
-	ret = setsockopt(con->write_queue.bfd.fd, IPPROTO_TCP, TCP_NODELAY, &on, sizeof(on));
-	if (ret != 0)
-                LOGP(DMSC, LOGL_ERROR, "Failed to set TCP_NODELAY: %s\n", strerror(errno));
+//	ret = setsockopt(con->write_queue.bfd.fd, IPPROTO_TCP, TCP_NODELAY, &on, sizeof(on));
+//	if (ret != 0)
+//                LOGP(DMSC, LOGL_ERROR, "Failed to set TCP_NODELAY: %s\n", strerror(errno));
 
-	data = (struct bsc_msc_data *) con->write_queue.bfd.data;
-	msc_ping_timeout_cb(data);
+//	data = (struct bsc_msc_data *) con->write_queue.bfd.data;
+//	msc_ping_timeout_cb(data);
 
 	sig.data = data;
 	osmo_signal_dispatch(SS_MSC, S_MSC_CONNECTED, &sig);
@@ -385,20 +391,20 @@
  */
 static void msc_connection_was_lost(struct bsc_msc_connection *msc)
 {
-	struct msc_signal_data sig;
-	struct bsc_msc_data *data;
+//	struct msc_signal_data sig;
+//	struct bsc_msc_data *data;
 
 	LOGP(DMSC, LOGL_ERROR, "Lost MSC connection. Freing stuff.\n");
 
-	data = (struct bsc_msc_data *) msc->write_queue.bfd.data;
-	osmo_timer_del(&data->ping_timer);
-	osmo_timer_del(&data->pong_timer);
-
-	sig.data = data;
-	osmo_signal_dispatch(SS_MSC, S_MSC_LOST, &sig);
+//	data = (struct bsc_msc_data *) msc->write_queue.bfd.data;
+//	osmo_timer_del(&data->ping_timer);
+//	osmo_timer_del(&data->pong_timer);
+//
+//	sig.data = data;
+//	osmo_signal_dispatch(SS_MSC, S_MSC_LOST, &sig);
 
 	msc->is_authenticated = 0;
-	bsc_msc_schedule_connect(msc);
+//	bsc_msc_schedule_connect(msc);
 }
 
 static void send_lacs(struct gsm_network *net, struct bsc_msc_connection *conn)
@@ -515,6 +521,8 @@
 	osmo_signal_dispatch(SS_MSC, S_MSC_AUTHENTICATED, &sig);
 }
 
+#endif 
+
 int osmo_bsc_msc_init(struct bsc_msc_data *data)
 {
 	if (mgcp_create_port(data) != 0)
@@ -526,19 +534,24 @@
 		return -1;
 	}
 
-	osmo_timer_setup(&data->ping_timer, msc_ping_timeout_cb, data);
-	osmo_timer_setup(&data->pong_timer, msc_pong_timeout_cb, data);
+//	osmo_timer_setup(&data->ping_timer, msc_ping_timeout_cb, data);
+//	osmo_timer_setup(&data->pong_timer, msc_pong_timeout_cb, data);
 
 	data->msc_con->write_queue.bfd.data = data;
-	data->msc_con->connection_loss = msc_connection_was_lost;
-	data->msc_con->connected = msc_connection_connected;
-	data->msc_con->write_queue.read_cb = ipaccess_a_fd_cb;
-	data->msc_con->write_queue.write_cb = msc_alink_do_write;
-	bsc_msc_connect(data->msc_con);
+//	data->msc_con->connection_loss = msc_connection_was_lost;
+//	data->msc_con->connected = msc_connection_connected;
+//	data->msc_con->write_queue.read_cb = ipaccess_a_fd_cb;
+//	data->msc_con->write_queue.write_cb = msc_alink_do_write;
+//	bsc_msc_connect(data->msc_con);
+
+	data->msc_con->is_connected = 1;
+	data->msc_con->is_authenticated = 1;
+
 
 	return 0;
 }
 
+
 struct bsc_msc_data *osmo_msc_data_find(struct gsm_network *net, int nr)
 {
 	struct bsc_msc_data *msc_data;
@@ -584,3 +597,4 @@
 
 	return msc_data;
 }
+
diff --git a/src/osmo-bsc/osmo_bsc_reset.c b/src/osmo-bsc/osmo_bsc_reset.c
new file mode 100644
index 0000000..0baf080
--- /dev/null
+++ b/src/osmo-bsc/osmo_bsc_reset.c
@@ -0,0 +1,190 @@
+/* (C) 2017 by sysmocom s.f.m.c. GmbH
+ * All Rights Reserved
+ *
+ * Author: Philipp Maier
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include <osmocom/core/logging.h>
+#include <osmocom/core/utils.h>
+#include <osmocom/core/timer.h>
+#include <osmocom/core/fsm.h>
+#include <unistd.h>
+#include <errno.h>
+#include <string.h>
+#include <openbsc/debug.h>
+#include <openbsc/bsc_msc_data.h>
+#include <openbsc/osmo_bsc_sigtran.h>
+
+#define RESET_RESEND_INTERVAL 2	/* sec */
+#define RESET_RESEND_TIMER_NO 1234	/* FIXME: dig out the real timer number */
+#define BAD_CONNECTION_THRESOLD 3	/* connection failures */
+
+enum fsm_states {
+	ST_DISC,		/* Disconnected from MSC */
+	ST_CONN,		/* We have a confirmed connection to the MSC */
+};
+
+static const struct value_string fsm_state_names[] = {
+	{ST_DISC, "ST_DISC (disconnected)"},
+	{ST_CONN, "ST_CONN (connected)"},
+	{0, NULL},
+};
+
+enum fsm_evt {
+	EV_RESET_ACK,		/* got reset acknowlegement from the MSC */
+	EV_N_DISCONNECT,	/* lost a connection */
+	EV_N_CONNECT,		/* made a successful connection */
+};
+
+static const struct value_string fsm_evt_names[] = {
+	{EV_RESET_ACK, "EV_RESET_ACK"},
+	{EV_N_DISCONNECT, "EV_N_DISCONNECT"},
+	{EV_N_CONNECT, "EV_N_CONNECT"},
+	{0, NULL},
+};
+
+/* Disconnected state */
+static void fsm_disc_cb(struct osmo_fsm_inst *fi, uint32_t event, void *data)
+{
+	struct bsc_msc_data *msc = (struct bsc_msc_data *)data;
+
+	LOGP(DMSC, LOGL_NOTICE, "fsm-state (msc-reset): %s, fsm-event: %s, MSC No.: %i\n",
+	     get_value_string(fsm_state_names, ST_DISC), get_value_string(fsm_evt_names, event), msc->nr);
+	msc->msc_con->msc_conn_loss_count = 0;
+	osmo_fsm_inst_state_chg(fi, ST_CONN, 0, 0);
+}
+
+/* Connected state */
+static void fsm_conn_cb(struct osmo_fsm_inst *fi, uint32_t event, void *data)
+{
+	struct bsc_msc_data *msc = (struct bsc_msc_data *)data;
+
+	LOGP(DMSC, LOGL_NOTICE, "fsm-state (msc-reset): %s, fsm-event: %s, MSC No.: %i\n",
+	     get_value_string(fsm_state_names, ST_CONN), get_value_string(fsm_evt_names, event), msc->nr);
+
+	OSMO_ASSERT(msc);
+
+	switch (event) {
+	case EV_N_DISCONNECT:
+		if (msc->msc_con->msc_conn_loss_count >= BAD_CONNECTION_THRESOLD) {
+			LOGP(DMSC, LOGL_NOTICE, "SIGTRAN connection to MSC No.: %i down, reconnecting...\n", msc->nr);
+			osmo_fsm_inst_state_chg(fi, ST_DISC, RESET_RESEND_INTERVAL, RESET_RESEND_TIMER_NO);
+		} else
+			msc->msc_con->msc_conn_loss_count++;
+		break;
+	case EV_N_CONNECT:
+		msc->msc_con->msc_conn_loss_count = 0;
+		break;
+	}
+}
+
+/* Timer callback to retransmit the reset signal */
+static int fsm_reset_ack_timeout_cb(struct osmo_fsm_inst *fi)
+{
+	struct bsc_msc_data *msc = (struct bsc_msc_data *)fi->priv;
+
+	LOGP(DMSC, LOGL_NOTICE, "reset-ack timeout (T%i) in state %s, MSC No.: %i, resending...\n", fi->T,
+	     get_value_string(fsm_state_names, fi->state), msc->nr);
+
+	osmo_bsc_sigtran_reset(msc);
+	osmo_bsc_sigtran_tx_reset(msc);
+
+	osmo_fsm_inst_state_chg(fi, ST_DISC, RESET_RESEND_INTERVAL, RESET_RESEND_TIMER_NO);
+	return 0;
+}
+
+static struct osmo_fsm_state fsm_states[] = {
+	[ST_DISC] = {
+		     .in_event_mask = (1 << EV_RESET_ACK),
+		     .out_state_mask = (1 << ST_DISC) | (1 << ST_CONN),
+		     .name = "DISC",
+		     .action = fsm_disc_cb,
+		     },
+	[ST_CONN] = {
+		     .in_event_mask = (1 << EV_N_DISCONNECT) | (1 << EV_N_CONNECT),
+		     .out_state_mask = (1 << ST_DISC) | (1 << ST_CONN),
+		     .name = "CONN",
+		     .action = fsm_conn_cb,
+		     },
+};
+
+/* State machine definition */
+static struct osmo_fsm fsm = {
+	.name = "FSM RESET",
+	.states = fsm_states,
+	.num_states = ARRAY_SIZE(fsm_states),
+	.log_subsys = DMSC,
+	.timer_cb = fsm_reset_ack_timeout_cb,
+};
+
+/* Create and start state machine which handles the reset/reset-ack procedure */
+void start_reset_fsm(struct bsc_msc_data *msc)
+{
+	OSMO_ASSERT(msc);
+	OSMO_ASSERT(msc->msc_con);
+
+	osmo_fsm_register(&fsm);
+	msc->msc_con->fsm_reset = osmo_fsm_inst_alloc(&fsm, NULL, NULL, LOGL_DEBUG, "FSM RESET INST");
+	OSMO_ASSERT(msc->msc_con->fsm_reset);
+
+	msc->msc_con->fsm_reset->priv = msc;
+
+	/* kick off reset-ack sending mechanism */
+	osmo_fsm_inst_state_chg(msc->msc_con->fsm_reset, ST_DISC, RESET_RESEND_INTERVAL, RESET_RESEND_TIMER_NO);
+}
+
+/* Confirm that we sucessfully received a reset acknowlege message */
+void reset_ack_confirm(struct bsc_msc_data *msc)
+{
+	OSMO_ASSERT(msc);
+	OSMO_ASSERT(msc->msc_con);
+	OSMO_ASSERT(msc->msc_con->fsm_reset);
+
+	osmo_fsm_inst_dispatch(msc->msc_con->fsm_reset, EV_RESET_ACK, msc);
+}
+
+/* Report a failed connection */
+void report_conn_fail(struct bsc_msc_data *msc)
+{
+	OSMO_ASSERT(msc);
+	OSMO_ASSERT(msc->msc_con);
+	OSMO_ASSERT(msc->msc_con->fsm_reset);
+
+	osmo_fsm_inst_dispatch(msc->msc_con->fsm_reset, EV_N_DISCONNECT, msc);
+}
+
+/* Report a successful connection */
+void report_conn_success(struct bsc_msc_data *msc)
+{
+	OSMO_ASSERT(msc);
+	OSMO_ASSERT(msc->msc_con);
+	OSMO_ASSERT(msc->msc_con->fsm_reset);
+
+	osmo_fsm_inst_dispatch(msc->msc_con->fsm_reset, EV_N_CONNECT, msc);
+}
+
+/* Check if we have a connection to a specified msc */
+bool sccp_conn_ready(struct bsc_msc_data *msc)
+{
+	OSMO_ASSERT(msc);
+	OSMO_ASSERT(msc->msc_con);
+	OSMO_ASSERT(msc->msc_con->fsm_reset);
+	if (msc->msc_con->fsm_reset->state == ST_CONN)
+		return true;
+
+	return false;
+}
diff --git a/src/osmo-bsc/osmo_bsc_sccp.c b/src/osmo-bsc/osmo_bsc_sccp.c
deleted file mode 100644
index e242390..0000000
--- a/src/osmo-bsc/osmo_bsc_sccp.c
+++ /dev/null
@@ -1,328 +0,0 @@
-/* Interaction with the SCCP subsystem */
-/*
- * (C) 2009-2014 by Holger Hans Peter Freyther <zecke@selfish.org>
- * (C) 2009-2014 by On-Waves
- * All Rights Reserved
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU Affero General Public License as published by
- * the Free Software Foundation; either version 3 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU Affero General Public License for more details.
- *
- * You should have received a copy of the GNU Affero General Public License
- * along with this program.  If not, see <http://www.gnu.org/licenses/>.
- *
- */
-
-#include <openbsc/gsm_data.h>
-#include <openbsc/osmo_bsc.h>
-#include <openbsc/osmo_bsc_grace.h>
-#include <openbsc/bsc_msc_data.h>
-#include <openbsc/gsm_04_80.h>
-#include <openbsc/debug.h>
-#include <openbsc/ipaccess.h>
-#include <openbsc/signal.h>
-
-#include <osmocom/core/talloc.h>
-#include <osmocom/gsm/gsm0808.h>
-#include <osmocom/gsm/protocol/gsm_08_08.h>
-
-#include <osmocom/sccp/sccp.h>
-
-/* SCCP helper */
-#define SCCP_IT_TIMER 60
-
-static LLIST_HEAD(active_connections);
-
-static void free_queued(struct osmo_bsc_sccp_con *conn)
-{
-	struct msgb *msg;
-
-	while (!llist_empty(&conn->sccp_queue)) {
-		/* this is not allowed to fail */
-		msg = msgb_dequeue(&conn->sccp_queue);
-		msgb_free(msg);
-	}
-
-	conn->sccp_queue_size = 0;
-}
-
-static void send_queued(struct osmo_bsc_sccp_con *conn)
-{
-	struct msgb *msg;
-
-	while (!llist_empty(&conn->sccp_queue)) {
-		/* this is not allowed to fail */
-		msg = msgb_dequeue(&conn->sccp_queue);
-		sccp_connection_write(conn->sccp, msg);
-		msgb_free(msg);
-		conn->sccp_queue_size -= 1;
-	}
-}
-
-static void msc_outgoing_sccp_data(struct sccp_connection *conn,
-				   struct msgb *msg, unsigned int len)
-{
-	struct osmo_bsc_sccp_con *bsc_con =
-			(struct osmo_bsc_sccp_con *) conn->data_ctx;
-
-	bsc_handle_dt1(bsc_con, msg, len);
-}
-
-static void msc_outgoing_sccp_state(struct sccp_connection *conn, int old_state)
-{
-	struct osmo_bsc_sccp_con *con_data;
-
-	if (conn->connection_state >= SCCP_CONNECTION_STATE_RELEASE_COMPLETE) {
-		con_data = (struct osmo_bsc_sccp_con *) conn->data_ctx;
-		if (con_data->conn) {
-			LOGP(DMSC, LOGL_ERROR,
-				"ERROR: The lchan is still associated.\n");
-			gsm0808_clear(con_data->conn);
-			bsc_subscr_con_free(con_data->conn);
-			con_data->conn = NULL;
-		}
-
-		con_data->sccp = NULL;
-		free_queued(con_data);
-		sccp_connection_free(conn);
-		bsc_delete_connection(con_data);
-	} else if (conn->connection_state == SCCP_CONNECTION_STATE_ESTABLISHED) {
-		LOGP(DMSC, LOGL_DEBUG, "Connection established: %p\n", conn);
-		con_data = (struct osmo_bsc_sccp_con *) conn->data_ctx;
-
-		osmo_timer_del(&con_data->sccp_cc_timeout);
-		osmo_timer_schedule(&con_data->sccp_it_timeout, SCCP_IT_TIMER, 0);
-
-		send_queued(con_data);
-	}
-}
-
-static void bsc_sccp_force_free(struct osmo_bsc_sccp_con *data)
-{
-	if (data->conn) {
-		gsm0808_clear(data->conn);
-		bsc_subscr_con_free(data->conn);
-		data->conn = NULL;
-	}
-
-	free_queued(data);
-	sccp_connection_force_free(data->sccp);
-	data->sccp = NULL;
-	bsc_delete_connection(data);
-}
-
-static void sccp_it_timeout(void *_data)
-{
-	struct osmo_bsc_sccp_con *data =
-		(struct osmo_bsc_sccp_con *) _data;
-
-	sccp_connection_send_it(data->sccp);
-	osmo_timer_schedule(&data->sccp_it_timeout, SCCP_IT_TIMER, 0);
-}
-
-static void sccp_cc_timeout(void *_data)
-{
-	struct osmo_bsc_sccp_con *data =
-		(struct osmo_bsc_sccp_con *) _data;
-
-	if (data->sccp->connection_state >= SCCP_CONNECTION_STATE_ESTABLISHED)
-		return;
-
-	LOGP(DMSC, LOGL_ERROR, "The connection was never established.\n");
-	bsc_sccp_force_free(data);
-}
-
-static void msc_sccp_write_ipa(struct sccp_connection *conn, struct msgb *msg,
-			      void *global_ctx, void *ctx)
-{
-	struct bsc_msc_connection *msc_con;
-
-	if (conn) {
-		struct osmo_bsc_sccp_con *bsc_con = conn->data_ctx;
-		msc_con = bsc_con->msc->msc_con;
-		if (bsc_con->send_ping) {
-			bsc_con->send_ping = 0;
-			msc_queue_write_with_ping(msc_con, msg, IPAC_PROTO_SCCP);
-			return;
-		}
-	} else {
-		msc_con = ctx;
-	}
-
-	msc_queue_write(msc_con, msg, IPAC_PROTO_SCCP);
-}
-
-static int msc_sccp_accept(struct sccp_connection *connection, void *data)
-{
-	LOGP(DMSC, LOGL_DEBUG, "Rejecting incoming SCCP connection.\n");
-	return -1;
-}
-
-static int msc_sccp_read(struct msgb *msgb, unsigned int length, void *data)
-{
-	struct bsc_msc_data *msc = (struct bsc_msc_data *) msgb->cb[0];
-	return bsc_handle_udt(msc, msgb, length);
-}
-
-int bsc_queue_for_msc(struct osmo_bsc_sccp_con *conn, struct msgb *msg)
-{
-	struct sccp_connection *sccp = conn->sccp;
-
-	if (sccp->connection_state > SCCP_CONNECTION_STATE_ESTABLISHED) {
-		LOGP(DMSC, LOGL_ERROR, "Connection closing, dropping packet on: %p\n", sccp);
-		msgb_free(msg);
-	} else if (sccp->connection_state == SCCP_CONNECTION_STATE_ESTABLISHED
-		   && conn->sccp_queue_size == 0) {
-		sccp_connection_write(sccp, msg);
-		msgb_free(msg);
-	} else if (conn->sccp_queue_size > 10) {
-		LOGP(DMSC, LOGL_ERROR, "Connection closing, dropping packet on: %p\n", sccp);
-		msgb_free(msg);
-	} else {
-		LOGP(DMSC, LOGL_DEBUG, "Queueing packet on %p. Queue size: %d\n", sccp, conn->sccp_queue_size);
-		conn->sccp_queue_size += 1;
-		msgb_enqueue(&conn->sccp_queue, msg);
-	}
-
-	return 0;
-}
-
-enum bsc_con bsc_create_new_connection(struct gsm_subscriber_connection *conn,
-			      struct bsc_msc_data *msc, int send_ping)
-{
-	struct osmo_bsc_sccp_con *bsc_con;
-	struct sccp_connection *sccp;
-
-	/* This should not trigger */
-	if (!msc || !msc->msc_con->is_authenticated) {
-		LOGP(DMSC, LOGL_ERROR,
-		     "How did this happen? MSC is not connected. Dropping.\n");
-		return BSC_CON_REJECT_NO_LINK;
-	}
-
-	if (!bsc_grace_allow_new_connection(conn->bts->network, conn->bts)) {
-		LOGP(DMSC, LOGL_NOTICE, "BSC in grace period. No new connections.\n");
-		return BSC_CON_REJECT_RF_GRACE;
-	}
-
-	sccp = sccp_connection_socket();
-	if (!sccp) {
-		LOGP(DMSC, LOGL_ERROR, "Failed to allocate memory.\n");
-		return BSC_CON_NO_MEM;
-	}
-
-	bsc_con = talloc_zero(conn->bts, struct osmo_bsc_sccp_con);
-	if (!bsc_con) {
-		LOGP(DMSC, LOGL_ERROR, "Failed to allocate.\n");
-		sccp_connection_free(sccp);
-		return BSC_CON_NO_MEM;
-	}
-
-	/* callbacks */
-	sccp->state_cb = msc_outgoing_sccp_state;
-	sccp->data_cb = msc_outgoing_sccp_data;
-	sccp->data_ctx = bsc_con;
-
-	bsc_con->send_ping = send_ping;
-
-	/* prepare the timers */
-	osmo_timer_setup(&bsc_con->sccp_it_timeout, sccp_it_timeout, bsc_con);
-	osmo_timer_setup(&bsc_con->sccp_cc_timeout, sccp_cc_timeout, bsc_con);
-
-	INIT_LLIST_HEAD(&bsc_con->sccp_queue);
-
-	bsc_con->sccp = sccp;
-	bsc_con->msc = msc;
-	bsc_con->conn = conn;
-	llist_add_tail(&bsc_con->entry, &active_connections);
-	conn->sccp_con = bsc_con;
-	return BSC_CON_SUCCESS;
-}
-
-int bsc_open_connection(struct osmo_bsc_sccp_con *conn, struct msgb *msg)
-{
-	osmo_timer_schedule(&conn->sccp_cc_timeout, 10, 0);
-	sccp_connection_connect(conn->sccp, &sccp_ssn_bssap, msg);
-	msgb_free(msg);
-	return 0;
-}
-
-int bsc_delete_connection(struct osmo_bsc_sccp_con *sccp)
-{
-	if (!sccp)
-		return 0;
-
-	if (sccp->conn)
-		LOGP(DMSC, LOGL_ERROR, "Should have been cleared.\n");
-
-	llist_del(&sccp->entry);
-	osmo_timer_del(&sccp->sccp_it_timeout);
-	osmo_timer_del(&sccp->sccp_cc_timeout);
-	talloc_free(sccp);
-	return 0;
-}
-
-static void bsc_notify_msc_lost(struct osmo_bsc_sccp_con *con)
-{
-	struct gsm_subscriber_connection *conn = con->conn;
-
-	/* send USSD notification if string configured and con->data is set */
-	if (!conn)
-		return;
-
-	/* check for config string */
-	if (!con->msc->ussd_msc_lost_txt)
-		return;
-	if (con->msc->ussd_msc_lost_txt[0] == '\0')
-		return;
-
-	/* send USSD notification */
-	bsc_send_ussd_notify(conn, 1, conn->sccp_con->msc->ussd_msc_lost_txt);
-	bsc_send_ussd_release_complete(conn);
-}
-
-static void bsc_notify_and_close_conns(struct bsc_msc_connection *msc_con)
-{
-	struct osmo_bsc_sccp_con *con, *tmp;
-
-	llist_for_each_entry_safe(con, tmp, &active_connections, entry) {
-		if (con->msc->msc_con != msc_con)
-			continue;
-
-		bsc_notify_msc_lost(con);
-		bsc_sccp_force_free(con);
-	}
-}
-
-static int handle_msc_signal(unsigned int subsys, unsigned int signal,
-			     void *handler_data, void *signal_data)
-{
-	struct msc_signal_data *msc;
-
-	if (subsys != SS_MSC)
-		return 0;
-
-	msc = signal_data;
-	if (signal == S_MSC_LOST)
-		bsc_notify_and_close_conns(msc->data->msc_con);
-
-	return 0;
-}
-
-int osmo_bsc_sccp_init(struct gsm_network *gsmnet)
-{
-	sccp_set_log_area(DSCCP);
-	sccp_system_init(msc_sccp_write_ipa, gsmnet);
-	sccp_connection_set_incoming(&sccp_ssn_bssap, msc_sccp_accept, NULL);
-	sccp_set_read(&sccp_ssn_bssap, msc_sccp_read, gsmnet);
-
-	osmo_signal_register_handler(SS_MSC, handle_msc_signal, gsmnet);
-
-	return 0;
-}
diff --git a/src/osmo-bsc/osmo_bsc_sigtran.c b/src/osmo-bsc/osmo_bsc_sigtran.c
new file mode 100644
index 0000000..0f6ca33
--- /dev/null
+++ b/src/osmo-bsc/osmo_bsc_sigtran.c
@@ -0,0 +1,561 @@
+/* (C) 2017 by sysmocom s.f.m.c. GmbH
+ * All Rights Reserved
+ *
+ * Author: Philipp Maier
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include <osmocom/core/utils.h>
+#include <osmocom/core/logging.h>
+#include <osmocom/sigtran/osmo_ss7.h>
+#include <osmocom/sigtran/sccp_sap.h>
+#include <osmocom/sccp/sccp_types.h>
+#include <osmocom/core/linuxlist.h>
+#include <osmocom/gsm/gsm0808.h>
+#include <osmocom/core/msgb.h>
+#include <openbsc/bsc_msc_data.h>
+#include <openbsc/debug.h>
+#include <openbsc/osmo_bsc.h>
+#include <openbsc/osmo_bsc_grace.h>
+#include <openbsc/osmo_bsc_sigtran.h>
+#include <openbsc/a_reset.h>
+#include <openbsc/gsm_04_80.h>
+
+/* A pointer to a list with all involved MSCs
+ * (a copy of the pointer location submitted with osmo_bsc_sigtran_init() */
+static struct llist_head *msc_list;
+
+#define RESET_INTERVAL 1	/* sek */
+#define SCCP_MSG_MAXSIZE 1024
+#define CS7_POINTCODE_DEFAULT_OFFSET 2
+
+/* Internal list with connections we currently maintain. This
+ * list is of type struct osmo_bsc_sccp_con */
+static LLIST_HEAD(active_connections);
+
+/* The SCCP stack will not assign connection IDs to us automatically, we
+ * will do this ourselves using a counter variable, that counts one up
+ * for every new connection */
+static uint32_t conn_id_counter;
+
+/* Helper function to Check if the given connection id is already assigned */
+static struct osmo_bsc_sccp_con *get_bsc_conn_by_conn_id(int conn_id)
+{
+	conn_id &= 0xFFFFFF;
+	struct osmo_bsc_sccp_con *bsc_con;
+
+	llist_for_each_entry(bsc_con, &active_connections, entry) {
+		if (bsc_con->conn_id == conn_id)
+			return bsc_con;
+	}
+
+	return NULL;
+}
+
+/* Pick a free connection id */
+static int pick_free_conn_id(const struct bsc_msc_data *msc)
+{
+	int conn_id = conn_id_counter;
+	int i;
+
+	for (i = 0; i < 0xFFFFFF; i++) {
+		conn_id++;
+		conn_id &= 0xFFFFFF;
+		if (get_bsc_conn_by_conn_id(conn_id) == false) {
+			conn_id_counter = conn_id;
+			return conn_id;
+		}
+	}
+
+	return -1;
+}
+
+/* Send reset to MSC */
+static void osmo_bsc_sigtran_tx_reset(const struct bsc_msc_data *msc)
+{
+	struct osmo_ss7_instance *ss7;
+	struct msgb *msg;
+
+	ss7 = osmo_ss7_instance_find(msc->a.cs7_instance);
+	OSMO_ASSERT(ss7);
+	LOGP(DMSC, LOGL_NOTICE, "Sending RESET to MSC: %s\n", osmo_sccp_addr_name(ss7, &msc->a.msc_addr));
+	msg = gsm0808_create_reset();
+	osmo_sccp_tx_unitdata_msg(msc->a.sccp_user, &msc->a.bsc_addr,
+				  &msc->a.msc_addr, msg);
+}
+
+/* Send reset-ack to MSC */
+void osmo_bsc_sigtran_tx_reset_ack(const struct bsc_msc_data *msc)
+{
+	struct osmo_ss7_instance *ss7;
+	struct msgb *msg;
+	OSMO_ASSERT(msc);
+
+	ss7 = osmo_ss7_instance_find(msc->a.cs7_instance);
+	OSMO_ASSERT(ss7);
+	LOGP(DMSC, LOGL_NOTICE, "Sending RESET ACK to MSC: %s\n", osmo_sccp_addr_name(ss7, &msc->a.msc_addr));
+	msg = gsm0808_create_reset_ack();
+	osmo_sccp_tx_unitdata_msg(msc->a.sccp_user, &msc->a.bsc_addr,
+				  &msc->a.msc_addr, msg);
+}
+
+/* Find an MSC by its sigtran point code */
+static struct bsc_msc_data *get_msc_by_addr(const struct osmo_sccp_addr *msc_addr)
+{
+	struct osmo_ss7_instance *ss7;
+	struct bsc_msc_data *msc;
+	llist_for_each_entry(msc, msc_list, entry) {
+		if (memcmp(msc_addr, &msc->a.msc_addr, sizeof(*msc_addr)) == 0)
+			return msc;
+	}
+
+	ss7 = osmo_ss7_instance_find(msc->a.cs7_instance);
+	OSMO_ASSERT(ss7);
+	LOGP(DMSC, LOGL_ERROR, "Unable to find MSC data under address: %s\n", osmo_sccp_addr_name(ss7, msc_addr));
+	return NULL;
+}
+
+/* Send data to MSC, use the connection id which MSC it is */
+static int handle_data_from_msc(int conn_id, struct msgb *msg)
+{
+	struct osmo_bsc_sccp_con *bsc_con = get_bsc_conn_by_conn_id(conn_id);
+	int rc = -EINVAL;
+
+	if (bsc_con) {
+		msg->l3h = msgb_l2(msg);
+		rc = bsc_handle_dt(bsc_con, msg, msgb_l2len(msg));
+	} else
+		LOGP(DMSC, LOGL_NOTICE, "incoming data from unknown connection id: %i\n", conn_id);
+
+	return rc;
+}
+
+/* Sent unitdata to MSC, use the point code to determine which MSC it is */
+static int handle_unitdata_from_msc(const struct osmo_sccp_addr *msc_addr, struct msgb *msg,
+				    const struct osmo_sccp_user *scu)
+{
+	struct osmo_ss7_instance *ss7;
+	struct bsc_msc_data *msc = get_msc_by_addr(msc_addr);
+	int rc = -EINVAL;
+
+	if (msc) {
+		msg->l3h = msgb_l2(msg);
+		rc = bsc_handle_udt(msc, msg, msgb_l2len(msg));
+	} else {
+		ss7 = osmo_sccp_get_ss7(osmo_sccp_get_sccp(scu));
+		OSMO_ASSERT(ss7);
+		LOGP(DMSC, LOGL_NOTICE, "incoming unitdata data from unknown remote address: %s\n",
+		     osmo_sccp_addr_name(ss7, msc_addr));
+	}
+	return rc;
+}
+
+/* Callback function, called by the SSCP stack when data arrives */
+static int sccp_sap_up(struct osmo_prim_hdr *oph, void *_scu)
+{
+	struct osmo_scu_prim *scu_prim = (struct osmo_scu_prim *)oph;
+	struct osmo_sccp_user *scu = _scu;
+	struct osmo_bsc_sccp_con *bsc_con;
+	int rc = 0;
+
+	switch (OSMO_PRIM_HDR(&scu_prim->oph)) {
+	case OSMO_PRIM(OSMO_SCU_PRIM_N_UNITDATA, PRIM_OP_INDICATION):
+		/* Handle inbound UNITDATA */
+		DEBUGP(DMSC, "N-UNITDATA.ind(%s)\n", osmo_hexdump(msgb_l2(oph->msg), msgb_l2len(oph->msg)));
+		rc = handle_unitdata_from_msc(&scu_prim->u.unitdata.calling_addr, oph->msg, scu);
+		break;
+
+	case OSMO_PRIM(OSMO_SCU_PRIM_N_CONNECT, PRIM_OP_INDICATION):
+		/* Handle (Reject) inbound connections */
+		DEBUGP(DMSC, "N-CONNECT.ind(X->%u)\n", scu_prim->u.connect.conn_id);
+		LOGP(DMSC, LOGL_DEBUG, "Rejecting inbound SCCP connection...\n");
+		rc = osmo_sccp_tx_disconn(scu, scu_prim->u.connect.conn_id, &scu_prim->u.connect.called_addr, 0);
+		break;
+
+	case OSMO_PRIM(OSMO_SCU_PRIM_N_CONNECT, PRIM_OP_CONFIRM):
+		/* Handle outbound connection confirmation */
+		if (msgb_l2len(oph->msg) > 0) {
+			DEBUGP(DMSC, "N-CONNECT.cnf(%u, %s)\n", scu_prim->u.connect.conn_id,
+			       osmo_hexdump(msgb_l2(oph->msg), msgb_l2len(oph->msg)));
+			rc = handle_data_from_msc(scu_prim->u.connect.conn_id, oph->msg);
+		} else
+			DEBUGP(DRANAP, "N-CONNECT.cnf(%u)\n", scu_prim->u.connect.conn_id);
+		break;
+
+	case OSMO_PRIM(OSMO_SCU_PRIM_N_DATA, PRIM_OP_INDICATION):
+		/* Handle incoming connection oriented data */
+		DEBUGP(DMSC, "N-DATA.ind(%u, %s)\n", scu_prim->u.data.conn_id,
+		       osmo_hexdump(msgb_l2(oph->msg), msgb_l2len(oph->msg)));
+
+		/* Incoming data is a sign of a vital connection */
+		bsc_con = get_bsc_conn_by_conn_id(scu_prim->u.disconnect.conn_id);
+		if (bsc_con)
+			a_reset_conn_success(bsc_con->msc->a.reset);
+
+		rc = handle_data_from_msc(scu_prim->u.data.conn_id, oph->msg);
+		break;
+
+	case OSMO_PRIM(OSMO_SCU_PRIM_N_DISCONNECT, PRIM_OP_INDICATION):
+		/* indication of disconnect */
+		if (msgb_l2len(oph->msg) > 0) {
+			DEBUGP(DMSC, "N-DISCONNECT.ind(%u, %s, cause=%i)\n", scu_prim->u.disconnect.conn_id,
+			       osmo_hexdump(msgb_l2(oph->msg), msgb_l2len(oph->msg)), scu_prim->u.disconnect.cause);
+			handle_data_from_msc(scu_prim->u.disconnect.conn_id, oph->msg);
+		} else
+			DEBUGP(DRANAP, "N-DISCONNECT.ind(%u, cause=%i)\n", scu_prim->u.disconnect.conn_id,
+			       scu_prim->u.disconnect.cause);
+
+		bsc_con = get_bsc_conn_by_conn_id(scu_prim->u.disconnect.conn_id);
+		if (bsc_con) {
+			/* We might have a connectivity problem. Maybe we need to go
+			 * through the reset procedure again? */
+			if (scu_prim->u.disconnect.cause == 0)
+				a_reset_conn_fail(bsc_con->msc->a.reset);
+
+			rc = osmo_bsc_sigtran_del_conn(bsc_con);
+		}
+		break;
+
+	default:
+		LOGP(DMSC, LOGL_ERROR, "Unhandled SIGTRAN primitive: %u:%u\n", oph->primitive, oph->operation);
+		break;
+	}
+
+	msgb_free(oph->msg);
+	return rc;
+}
+
+/* Allocate resources to make a new connection oriented sigtran connection
+ * (not the connection ittself!) */
+enum bsc_con osmo_bsc_sigtran_new_conn(struct gsm_subscriber_connection *conn, struct bsc_msc_data *msc)
+{
+	struct osmo_ss7_instance *ss7;
+	struct osmo_bsc_sccp_con *bsc_con;
+	int conn_id;
+
+	OSMO_ASSERT(conn);
+	OSMO_ASSERT(msc);
+
+	ss7 = osmo_ss7_instance_find(msc->a.cs7_instance);
+	OSMO_ASSERT(ss7);
+	LOGP(DMSC, LOGL_NOTICE, "Initializing resources for new SIGTRAN connection to MSC: %s...\n",
+	     osmo_sccp_addr_name(ss7, &msc->a.msc_addr));
+
+	if (a_reset_conn_ready(msc->a.reset) == false) {
+		LOGP(DMSC, LOGL_ERROR, "MSC is not connected. Dropping.\n");
+		return BSC_CON_REJECT_NO_LINK;
+	}
+
+	if (!bsc_grace_allow_new_connection(conn->bts->network, conn->bts)) {
+		LOGP(DMSC, LOGL_NOTICE, "BSC in grace period. No new connections.\n");
+		return BSC_CON_REJECT_RF_GRACE;
+	}
+
+	bsc_con = talloc_zero(conn->bts, struct osmo_bsc_sccp_con);
+	if (!bsc_con) {
+		LOGP(DMSC, LOGL_ERROR, "Failed to allocate new SIGTRAN connection.\n");
+		return BSC_CON_NO_MEM;
+	}
+
+	bsc_con->msc = msc;
+	bsc_con->conn = conn;
+	llist_add_tail(&bsc_con->entry, &active_connections);
+	conn->sccp_con = bsc_con;
+
+	/* Pick a free connection id */
+	conn_id = pick_free_conn_id(msc);
+	if (conn_id < 0)
+		return BSC_CON_REJECT_NO_LINK;
+	bsc_con->conn_id = conn_id;
+
+	LOGP(DMSC, LOGL_NOTICE, "Allocated new connection id: %i\n", conn_id);
+
+	return BSC_CON_SUCCESS;
+}
+
+/* Open a new connection oriented sigtran connection */
+int osmo_bsc_sigtran_open_conn(const struct osmo_bsc_sccp_con *conn, struct msgb *msg)
+{
+	struct osmo_ss7_instance *ss7;
+	struct bsc_msc_data *msc;
+	int conn_id;
+	int rc;
+
+	OSMO_ASSERT(conn);
+	OSMO_ASSERT(msg);
+	OSMO_ASSERT(conn->msc);
+
+	msc = conn->msc;
+
+	if (a_reset_conn_ready(msc->a.reset) == false) {
+		LOGP(DMSC, LOGL_ERROR, "MSC is not connected. Dropping.\n");
+		return -EINVAL;
+	}
+
+	conn_id = conn->conn_id;
+	ss7 = osmo_ss7_instance_find(msc->a.cs7_instance);
+	OSMO_ASSERT(ss7);
+	LOGP(DMSC, LOGL_NOTICE, "Opening new SIGTRAN connection (id=%i) to MSC: %s\n", conn_id,
+	     osmo_sccp_addr_name(ss7, &msc->a.msc_addr));
+
+	rc = osmo_sccp_tx_conn_req_msg(msc->a.sccp_user, conn_id, &msc->a.bsc_addr,
+				       &msc->a.msc_addr, msg);
+
+	return rc;
+}
+
+/* Send data to MSC */
+int osmo_bsc_sigtran_send(const struct osmo_bsc_sccp_con *conn, struct msgb *msg)
+{
+	struct osmo_ss7_instance *ss7;
+	int conn_id;
+	int rc;
+	struct bsc_msc_data *msc;
+
+	OSMO_ASSERT(conn);
+	OSMO_ASSERT(msg);
+	OSMO_ASSERT(conn->msc);
+
+	msc = conn->msc;
+
+	if (a_reset_conn_ready(msc->a.reset) == false) {
+		LOGP(DMSC, LOGL_ERROR, "MSC is not connected. Dropping.\n");
+		return -EINVAL;
+	}
+
+	conn_id = conn->conn_id;
+
+	ss7 = osmo_ss7_instance_find(msc->a.cs7_instance);
+	OSMO_ASSERT(ss7);
+	LOGP(DMSC, LOGL_DEBUG, "Sending connection (id=%i) oriented data to MSC: %si\n",
+	     conn_id, osmo_sccp_addr_name(ss7, &msc->a.msc_addr));
+
+	rc = osmo_sccp_tx_data_msg(msc->a.sccp_user, conn_id, msg);
+
+	return rc;
+}
+
+/* Delete a connection from the list with open connections
+ * (called by osmo_bsc_api.c on failing open connections and
+ * locally, when a connection is closed by the MSC */
+int osmo_bsc_sigtran_del_conn(struct osmo_bsc_sccp_con *conn)
+{
+	if (!conn)
+		return 0;
+
+	if (conn->conn) {
+		LOGP(DMSC, LOGL_ERROR,
+		     "sccp connection (id=%i) not cleared (gsm subscriber connection still active) -- forcefully clearing it now!\n",
+		     conn->conn_id);
+		bsc_subscr_con_free(conn->conn);
+		conn->conn = NULL;
+
+		/* This bahaviour might be caused by a bad connection. Maybe we
+		 * will have to go through the reset procedure again */
+		a_reset_conn_fail(conn->msc->a.reset);
+	}
+
+	llist_del(&conn->entry);
+	talloc_free(conn);
+
+	return 0;
+}
+
+/* Send an USSD notification in case we loose the connection to the MSC */
+static void bsc_notify_msc_lost(const struct osmo_bsc_sccp_con *conn)
+{
+	struct gsm_subscriber_connection *subscr_conn;
+
+	/* Check if sccp conn is still present */
+	if (!conn)
+		return;
+	subscr_conn = conn->conn;
+
+	/* send USSD notification if string configured and conn->data is set */
+	if (!subscr_conn)
+		return;
+
+	/* check for config string */
+	if (!conn->msc->ussd_msc_lost_txt)
+		return;
+	if (conn->msc->ussd_msc_lost_txt[0] == '\0')
+		return;
+
+	/* send USSD notification */
+	bsc_send_ussd_notify(subscr_conn, 1, subscr_conn->sccp_con->msc->ussd_msc_lost_txt);
+	bsc_send_ussd_release_complete(subscr_conn);
+}
+
+/* Close all open sigtran connections and channels */
+void osmo_bsc_sigtran_reset(const struct bsc_msc_data *msc)
+{
+	struct osmo_bsc_sccp_con *conn;
+	struct osmo_bsc_sccp_con *conn_temp;
+	OSMO_ASSERT(msc);
+
+	/* Close all open connections */
+	llist_for_each_entry_safe(conn, conn_temp, &active_connections, entry) {
+
+		/* We only may close connections which actually belong to this
+		 * MSC. All other open connections are left untouched */
+		if (conn->msc == msc) {
+			/* Notify active connection users via USSD that the MSC is down */
+			bsc_notify_msc_lost(conn);
+
+			/* Take down all occopied RF channels */
+			if (conn->conn)
+				gsm0808_clear(conn->conn);
+
+			/* Disconnect all Sigtran connections */
+			osmo_sccp_tx_disconn(msc->a.sccp_user, conn->conn_id, &msc->a.bsc_addr, 0);
+
+			/* Delete subscriber connection */
+			osmo_bsc_sigtran_del_conn(conn);
+		}
+	}
+}
+
+/* Callback function: Close all open connections */
+static void osmo_bsc_sigtran_reset_cb(const void *priv)
+{
+	struct bsc_msc_data *msc = (struct bsc_msc_data*) priv;
+
+	/* Shut down all ongoing traffic */
+	osmo_bsc_sigtran_reset(msc);
+
+	/* Send reset to MSC */
+	osmo_bsc_sigtran_tx_reset(msc);
+}
+
+/* Default point-code to be used as local address (BSC) */
+#define BSC_DEFAULT_PC "0.23.3"
+
+/* Default point-code to be used as remote address (MSC) */
+#define MSC_DEFAULT_PC "0.23.1"
+
+/* Initalize osmo sigtran backhaul */
+int osmo_bsc_sigtran_init(struct llist_head *mscs)
+{
+	bool free_attempt_used = false;
+	bool fail_on_next_invalid_cfg = false;
+
+	struct bsc_msc_data *msc;
+	char msc_name[32];
+	uint32_t default_pc;
+
+	OSMO_ASSERT(mscs);
+	msc_list = mscs;
+
+	llist_for_each_entry(msc, msc_list, entry) {
+		snprintf(msc_name, sizeof(msc_name), "msc-%u", msc->nr);
+		LOGP(DMSC, LOGL_NOTICE, "Initializing SCCP connection to MSC %s\n", msc_name);
+
+		/* Check if the VTY could determine a valid CS7 instance,
+		 * use safe default in case none is set */
+		if (msc->a.cs7_instance_valid == false) {
+			msc->a.cs7_instance = 0;
+			if (fail_on_next_invalid_cfg)
+				goto fail_auto_cofiguration;
+			free_attempt_used = true;
+		}
+		LOGP(DMSC, LOGL_NOTICE, "CS7 Instance identifier, A-Interface: %u\n", msc->a.cs7_instance);
+
+		/* Pre-Check if there is an ss7 instance present */
+		if (osmo_ss7_instance_find(msc->a.cs7_instance) == NULL) {
+			if (fail_on_next_invalid_cfg)
+				goto fail_auto_cofiguration;
+			free_attempt_used = true;
+		}
+
+		/* SS7 Protocol stack */
+		default_pc = osmo_ss7_pointcode_parse(NULL, BSC_DEFAULT_PC);
+		msc->a.sccp =
+		    osmo_sccp_simple_client_on_ss7_id(msc, msc->a.cs7_instance, msc_name, default_pc,
+						      OSMO_SS7_ASP_PROT_M3UA, 0, NULL, 0, NULL);
+		if (!msc->a.sccp)
+			return -EINVAL;
+
+		/* Check if the sccp-address fullfills minimum requirements (SSN+PC is present,
+		 * automatically recover addresses if the addresses are not set up properly) */
+		if (!osmo_sccp_check_addr(&msc->a.bsc_addr, OSMO_SCCP_ADDR_T_SSN | OSMO_SCCP_ADDR_T_PC)) {
+			if (fail_on_next_invalid_cfg)
+				goto fail_auto_cofiguration;
+			free_attempt_used = true;
+
+			LOGP(DMSC, LOGL_NOTICE,
+			     "A-interface: invalid or missing local (BSC) SCCP address (a.bsc_addr=%s)\n",
+			     osmo_sccp_addr_name(osmo_ss7_instance_find(msc->a.cs7_instance), &msc->a.bsc_addr));
+			osmo_sccp_local_addr_by_instance(&msc->a.bsc_addr, msc->a.sccp, SCCP_SSN_BSSAP);
+			LOGP(DMSC, LOGL_NOTICE,
+			     "A-interface: using automatically generated local (BSC) SCCP address (a.bsc_addr=%s)\n",
+			     osmo_sccp_addr_name(osmo_ss7_instance_find(msc->a.cs7_instance), &msc->a.bsc_addr));
+		} else {
+			LOGP(DMSC, LOGL_NOTICE,
+			     "A-interface: using local (BSC) automatically SCCP address (a.msc_addr=%s)\n",
+			     osmo_sccp_addr_name(osmo_ss7_instance_find(msc->a.cs7_instance), &msc->a.bsc_addr));
+		}
+
+		if (!osmo_sccp_check_addr(&msc->a.msc_addr, OSMO_SCCP_ADDR_T_SSN | OSMO_SCCP_ADDR_T_PC)) {
+			if (fail_on_next_invalid_cfg)
+				goto fail_auto_cofiguration;
+			free_attempt_used = true;
+
+			LOGP(DMSC, LOGL_NOTICE,
+			     "A-interface: invalid or missing remote (MSC) SCCP address for the MSC (a.msc_addr=%s)\n",
+			     osmo_sccp_addr_name(osmo_ss7_instance_find(msc->a.cs7_instance), &msc->a.msc_addr));
+			osmo_sccp_local_addr_by_instance(&msc->a.msc_addr, msc->a.sccp, SCCP_SSN_BSSAP);
+			msc->a.msc_addr.pc = osmo_ss7_pointcode_parse(NULL, MSC_DEFAULT_PC);
+			LOGP(DMSC, LOGL_NOTICE,
+			     "A-interface: using automatically generated remote (MSC) SCCP address (a.msc_addr=%s)\n",
+			     osmo_sccp_addr_name(osmo_ss7_instance_find(msc->a.cs7_instance), &msc->a.msc_addr));
+			free_attempt_used = true;
+		} else {
+			LOGP(DMSC, LOGL_NOTICE,
+			     "A-interface: using remote (MSC) automatically SCCP address (a.msc_addr=%s)\n",
+			     osmo_sccp_addr_name(osmo_ss7_instance_find(msc->a.cs7_instance), &msc->a.msc_addr));
+		}
+
+		/* Bind SCCP user */
+		msc->a.sccp_user = osmo_sccp_user_bind(msc->a.sccp, msc_name, sccp_sap_up, msc->a.bsc_addr.ssn);
+		if (!msc->a.sccp_user)
+			return -EINVAL;
+
+		/* Start MSC-Reset procedure */
+		msc->a.reset = a_reset_alloc(msc, msc_name, osmo_bsc_sigtran_reset_cb, msc);
+		if (!msc->a.reset)
+			return -EINVAL;
+
+		/* If we have detected that the SS7 configuration of the MSC we have just initalized
+		 * was incomplete or completely missing, we can not tolerate another incomplete
+		 * configuration. The reson for this is that we do only specify exactly one default
+		 * pointcode pair. We also specify localhost as default IP-Address. If we have wanted
+		 * to support multiple MSCs with automatic configuration we would be forced to invent
+		 * a complex ruleset how to allocate the pointcodes and respective IP-Addresses.
+		 * Furthermore, the situation where a single BSC is connected to multiple MSCs
+		 * is a very rare situation anyway. In this case we expect the user to experienced
+		 * enough to create a valid SS7/CS7 VTY configuration that does not lack any
+		 * components */
+		if (free_attempt_used)
+			fail_on_next_invalid_cfg = true;
+	}
+
+	return 0;
+
+fail_auto_cofiguration:
+	LOGP(DMSC, LOGL_ERROR,
+	     "A-interface: More than one invalid/inclomplete configuration detected, unable to revover - check config file!\n");
+	return -EINVAL;
+}
diff --git a/src/osmo-bsc/osmo_bsc_vty.c b/src/osmo-bsc/osmo_bsc_vty.c
index 2e2e99b..8edcbf3 100644
--- a/src/osmo-bsc/osmo_bsc_vty.c
+++ b/src/osmo-bsc/osmo_bsc_vty.c
@@ -28,6 +28,7 @@
 
 #include <osmocom/core/talloc.h>
 #include <osmocom/vty/logging.h>
+#include <osmocom/sccp/sccp_types.h>
 
 #include <time.h>
 
@@ -184,6 +185,16 @@
 
 	/* write amr options */
 	write_msc_amr_options(vty, msc);
+
+	/* write sccp connection configuration */
+	if (msc->a.bsc_addr_name) {
+		vty_out(vty, " bsc-addr %s%s",
+			msc->a.bsc_addr_name, VTY_NEWLINE);
+	}
+	if (msc->a.msc_addr_name) {
+		vty_out(vty, " msc-addr %s%s",
+			msc->a.msc_addr_name, VTY_NEWLINE);
+	}
 }
 
 static int config_write_msc(struct vty *vty)
@@ -685,6 +696,87 @@
 	return CMD_SUCCESS;
 }
 
+/* Make sure only standard SSN numbers are used. If no ssn number is
+ * configured, silently apply the default SSN */
+static void enforce_standard_ssn(struct vty *vty, struct osmo_sccp_addr *addr)
+{
+	if (addr->presence & OSMO_SCCP_ADDR_T_SSN) {
+		if (addr->ssn != SCCP_SSN_BSSAP)
+			vty_out(vty,
+				"setting an SSN (%u) different from the standard (%u) is not allowd, will use standard SSN for address: %s%s",
+				addr->ssn, SCCP_SSN_BSSAP, osmo_sccp_addr_dump(addr), VTY_NEWLINE);
+	}
+
+	addr->presence |= OSMO_SCCP_ADDR_T_SSN;
+	addr->ssn = SCCP_SSN_BSSAP;
+}
+
+DEFUN(cfg_msc_cs7_bsc_addr,
+      cfg_msc_cs7_bsc_addr_cmd,
+      "bsc-addr NAME",
+      "Calling Address (local address of this BSC)\n" "SCCP address name\n")
+{
+	struct bsc_msc_data *msc = bsc_msc_data(vty);
+	const char *bsc_addr_name = argv[0];
+	struct osmo_ss7_instance *ss7;
+
+	ss7 = osmo_sccp_addr_by_name(&msc->a.bsc_addr, bsc_addr_name);
+	if (!ss7) {
+		vty_out(vty, "No sccp address %s found%s", bsc_addr_name,
+			VTY_NEWLINE);
+		return CMD_WARNING;
+	}
+
+	/* Prevent mixing addresses from different CS7/SS7 instances */
+	if (msc->a.cs7_instance_valid) {
+		if (msc->a.cs7_instance != ss7->cfg.id) {
+			vty_out(vty,
+				"SCCP address %s from different CS7 instance%s",
+				bsc_addr_name, VTY_NEWLINE);
+			return CMD_WARNING;
+		}
+	}
+
+	msc->a.cs7_instance = ss7->cfg.id;
+	msc->a.cs7_instance_valid = true;
+	enforce_standard_ssn(vty, &msc->a.bsc_addr);
+	msc->a.bsc_addr_name = talloc_strdup(msc, bsc_addr_name);
+	return CMD_SUCCESS;
+}
+
+DEFUN(cfg_msc_cs7_msc_addr,
+      cfg_msc_cs7_msc_addr_cmd,
+      "msc-addr NAME",
+      "Called Address (remote address of the MSC)\n" "SCCP address name\n")
+{
+	struct bsc_msc_data *msc = bsc_msc_data(vty);
+	const char *msc_addr_name = argv[0];
+	struct osmo_ss7_instance *ss7;
+
+	ss7 = osmo_sccp_addr_by_name(&msc->a.msc_addr, msc_addr_name);
+	if (!ss7) {
+		vty_out(vty, "No sccp address %s found%s", msc_addr_name,
+			VTY_NEWLINE);
+		return CMD_WARNING;
+	}
+
+	/* Prevent mixing addresses from different CS7/SS7 instances */
+	if (msc->a.cs7_instance_valid) {
+		if (msc->a.cs7_instance != ss7->cfg.id) {
+			vty_out(vty,
+				"SCCP address %s from different CS7 instance%s",
+				msc_addr_name, VTY_NEWLINE);
+			return CMD_WARNING;
+		}
+	}
+
+	msc->a.cs7_instance = ss7->cfg.id;
+	msc->a.cs7_instance_valid = true;
+	enforce_standard_ssn(vty, &msc->a.msc_addr);
+	msc->a.msc_addr_name = talloc_strdup(msc, msc_addr_name);
+	return CMD_SUCCESS;
+}
+
 DEFUN(cfg_net_bsc_mid_call_text,
       cfg_net_bsc_mid_call_text_cmd,
       "mid-call-text .TEXT",
@@ -931,6 +1023,8 @@
 	install_element(MSC_NODE, &cfg_net_msc_amr_4_75_cmd);
 	install_element(MSC_NODE, &cfg_msc_acc_lst_name_cmd);
 	install_element(MSC_NODE, &cfg_msc_no_acc_lst_name_cmd);
+	install_element(MSC_NODE, &cfg_msc_cs7_bsc_addr_cmd);
+	install_element(MSC_NODE, &cfg_msc_cs7_msc_addr_cmd);
 
 	install_element_ve(&show_statistics_cmd);
 	install_element_ve(&show_mscs_cmd);
diff --git a/src/osmo-bsc_mgcp/Makefile.am b/src/osmo-bsc_mgcp/Makefile.am
index a19a4eb..b4e0d85 100644
--- a/src/osmo-bsc_mgcp/Makefile.am
+++ b/src/osmo-bsc_mgcp/Makefile.am
@@ -31,5 +31,6 @@
 	$(LIBOSMONETIF_LIBS) \
 	$(LIBBCG729_LIBS) \
 	$(LIBRARY_GSM) \
+	$(LIBOSMOSIGTRAN_LIBS) \
 	-lrt \
 	$(NULL)
diff --git a/src/osmo-bsc_nat/Makefile.am b/src/osmo-bsc_nat/Makefile.am
index be33d28..b7c13ad 100644
--- a/src/osmo-bsc_nat/Makefile.am
+++ b/src/osmo-bsc_nat/Makefile.am
@@ -53,6 +53,7 @@
 	$(LIBOSMOCTRL_LIBS) \
 	$(LIBOSMOABIS_LIBS) \
 	$(LIBOSMONETIF_LIBS) \
+	$(LIBOSMOSIGTRAN_LIBS) \
 	$(LIBCRYPTO_LIBS) \
 	-lrt \
 	$(NULL)
diff --git a/src/osmo-msc/msc_main.c b/src/osmo-msc/msc_main.c
index 723c0e6..cd713ee 100644
--- a/src/osmo-msc/msc_main.c
+++ b/src/osmo-msc/msc_main.c
@@ -63,6 +63,7 @@
 #include <openbsc/ctrl.h>
 #include <openbsc/osmo_bsc_rf.h>
 #include <openbsc/smpp.h>
+#include <osmocom/sigtran/osmo_ss7.h>
 #include <openbsc/mgcpgw_client.h>
 
 #include <openbsc/msc_ifaces.h>
@@ -70,6 +71,7 @@
 #include <openbsc/iu.h>
 #include <openbsc/iucs.h>
 #include <openbsc/iucs_ranap.h>
+#include <openbsc/a_iface.h>
 
 static const char * const osmomsc_copyright =
 	"OsmoMSC - Osmocom Circuit-Switched Core Network implementation\r\n"
@@ -310,8 +312,7 @@
 	.is_config_node	= bsc_vty_is_config_node,
 };
 
-static int rcvmsg_iu_cs(struct msgb *msg, struct gprs_ra_id *ra_id,
-			uint16_t *sai)
+static int rcvmsg_iu_cs(struct msgb *msg, struct gprs_ra_id *ra_id, uint16_t *sai)
 {
 	DEBUGP(DIUCS, "got IuCS message"
 	       " %d bytes: %s\n",
@@ -334,6 +335,68 @@
 	return iucs_rx_ranap_event(msc_network, ctx, type, data);
 }
 
+#define DEFAULT_M3UA_REMOTE_IP "127.0.0.1"
+#define DEFAULT_PC_A "0.23.1"
+#define DEFAULT_PC_IU "0.23.2"
+#define DEFAULT_PC_A_IU DEFAULT_PC_A
+
+static struct osmo_sccp_instance *sccp_setup(void *ctx, uint32_t cs7_instance,
+					     const char *label, const char *default_pc_str)
+{
+	int default_pc = osmo_ss7_pointcode_parse(NULL, default_pc_str);
+	if (default_pc < 0)
+		return NULL;
+
+	return osmo_sccp_simple_client_on_ss7_id(ctx, cs7_instance, label, default_pc,
+						 OSMO_SS7_ASP_PROT_M3UA,
+						 0, NULL, /* local: use arbitrary port and 0.0.0.0. */
+						 0, /* remote: use protocol default port */
+						 DEFAULT_M3UA_REMOTE_IP);
+	/* Note: If a differing remote IP is to be used, it was already entered in the vty config at
+	 * 'cs7' / 'asp' / 'remote-ip', and this default remote IP has no effect.
+	 * Similarly, 'cs7' / 'listen' can specify the local IP address. */
+}
+
+static int ss7_setup(void *ctx)
+{
+	uint32_t cs7_instance_a = msc_network->a.cs7_instance;
+#if BUILD_IU
+	uint32_t cs7_instance_iu = msc_network->iu.cs7_instance;
+
+	if (cs7_instance_a == cs7_instance_iu) {
+		/* Create one single SCCP instance which will be used for both,
+		 * Iu and A at the same time, under the same point-code */
+		LOGP(DMSC, LOGL_NOTICE, "CS7 Instance identifiers: A = Iu = %u\n", cs7_instance_a);
+
+		msc_network->a.sccp = sccp_setup(ctx, cs7_instance_a, "OsmoMSC-A-Iu", DEFAULT_PC_A_IU);
+		if (!msc_network->a.sccp)
+			return -EINVAL;
+
+		msc_network->iu.sccp = msc_network->a.sccp;
+	} else {
+		/* Create two separate SCCP instances to run A and Iu independently on different
+		 * pointcodes */
+		LOGP(DMSC, LOGL_NOTICE, "CS7 Instance identifiers: A = %u, Iu = %u\n",
+		     cs7_instance_a, cs7_instance_iu);
+
+		msc_network->a.sccp = sccp_setup(ctx, cs7_instance_a, "OsmoMSC-A", DEFAULT_PC_A);
+		if (!msc_network->a.sccp)
+			return -EINVAL;
+
+		msc_network->iu.sccp = sccp_setup(ctx, cs7_instance_iu, "OsmoMSC-Iu", DEFAULT_PC_IU);
+		if (!msc_network->iu.sccp)
+			return -EINVAL;
+	}
+#else
+	/* No Iu support, just open up an A instance */
+	msc_network->a.sccp = sccp_setup(ctx, cs7_instance_a, "OsmoMSC-A", DEFAULT_PC_A);
+	if (!msc_network->a.sccp)
+		return -EINVAL;
+#endif
+
+	return 0;
+}
+
 int main(int argc, char **argv)
 {
 	int rc;
@@ -349,6 +412,9 @@
 	/* For --version, vty_init() must be called before handling options */
 	vty_init(&msc_vty_info);
 
+	osmo_ss7_init();
+	osmo_ss7_vty_init_asp(tall_msc_ctx);
+
 	/* Parse options */
 	handle_options(argc, argv);
 
@@ -491,14 +557,19 @@
 		return 7;
 	}
 
-	/* Set up A-Interface */
-	/* TODO: implement A-Interface and remove above legacy stuff. */
+	if (ss7_setup(tall_msc_ctx)) {
+		printf("Setting up SCCP client failed.\n");
+		return 8;
+	}
 
 #ifdef BUILD_IU
 	/* Set up IuCS */
-	iu_init(tall_msc_ctx, "127.0.0.1", 14001, rcvmsg_iu_cs, rx_iu_event);
+	iu_init(tall_msc_ctx, msc_network->iu.sccp, rcvmsg_iu_cs, rx_iu_event);
 #endif
 
+	/* Set up A interface */
+	a_init(msc_network->a.sccp, msc_network);
+
 	if (msc_cmdline_config.daemonize) {
 		rc = osmo_daemonize();
 		if (rc < 0) {