diff --git a/openbsc/src/gprs/Makefile.am b/openbsc/src/gprs/Makefile.am
index 6d63145..31d3a10 100644
--- a/openbsc/src/gprs/Makefile.am
+++ b/openbsc/src/gprs/Makefile.am
@@ -13,6 +13,6 @@
 			$(top_srcdir)/src/socket.c $(top_srcdir)/src/debug.c
 osmo_gbproxy_LDADD = $(top_builddir)/src/libvty.a
 
-osmo_sgsn_SOURCES = sgsn_main.c sgsn_vty.c gprs_ns_vty.c \
+osmo_sgsn_SOURCES = sgsn_main.c sgsn_vty.c gprs_ns_vty.c sgsn_libgtp.c \
 			$(top_srcdir)/src/socket.c $(top_srcdir)/src/debug.c
-osmo_sgsn_LDADD = $(top_builddir)/src/libvty.a libsgsn.a
+osmo_sgsn_LDADD = $(top_builddir)/src/libvty.a libsgsn.a -lgtp
diff --git a/openbsc/src/gprs/gprs_gmm.c b/openbsc/src/gprs/gprs_gmm.c
index 4a42113..fc9d007 100644
--- a/openbsc/src/gprs/gprs_gmm.c
+++ b/openbsc/src/gprs/gprs_gmm.c
@@ -48,8 +48,10 @@
 #include <openbsc/gprs_llc.h>
 #include <openbsc/gprs_sgsn.h>
 
+/* Protocol related stuff, should go into libosmocore */
+
 /* 10.5.5.14 GPRS MM Cause / Table 10.5.147 */
-struct value_string gmm_cause_names[] = {
+const struct value_string gmm_cause_names[] = {
 	/* FIXME */
 	{ GMM_CAUSE_SEM_INCORR_MSG, "Semantically incorrect message" },
 	{ GMM_CAUSE_INV_MAND_INFO, "Invalid mandatory information" },
@@ -67,7 +69,7 @@
 };
 
 /* 10.5.6.6 SM Cause / Table 10.5.157 */
-struct value_string gsm_cause_names[] = {
+const struct value_string gsm_cause_names[] = {
 	{ GSM_CAUSE_INSUFF_RSRC, "Insufficient resources" },
 	{ GSM_CAUSE_MISSING_APN, "Missing or unknown APN" },
 	{ GSM_CAUSE_UNKNOWN_PDP, "Unknown PDP address or PDP type" },
@@ -101,34 +103,31 @@
 	{ 0, NULL }
 };
 
-static const char *att_name(uint8_t type)
-{
-	switch (type) {
-	case GPRS_ATT_T_ATTACH:
-		return "GPRS attach";
-	case GPRS_ATT_T_ATT_WHILE_IMSI:
-		return "GPRS attach while IMSI attached";
-	case GPRS_ATT_T_COMBINED:
-		return "Combined GPRS/IMSI attach";
-	default:
-		return "unknown";
-	}
-}
+/* 10.5.5.2 */
+const struct value_string gprs_att_t_strs[] = {
+	{ GPRS_ATT_T_ATTACH, 		"GPRS attach" },
+	{ GPRS_ATT_T_ATT_WHILE_IMSI, 	"GPRS attach while IMSI attached" },
+	{ GPRS_ATT_T_COMBINED, 		"Combined GPRS/IMSI attach" },
+	{ 0, NULL }
+};
 
-static const char *upd_name(uint8_t type)
-{
-	switch (type) {
-	case GPRS_UPD_T_RA:
-		return "RA updating";
-	case GPRS_UPD_T_RA_LA:
-		return "combined RA/LA updating";
-	case GPRS_UPD_T_RA_LA_IMSI_ATT:
-		return "combined RA/LA updating + IMSI attach";
-	case GPRS_UPD_T_PERIODIC:
-		return "periodic updating";
-	}
-	return "unknown";
-}
+const struct value_string gprs_upd_t_strs[] = {
+	{ GPRS_UPD_T_RA,		"RA updating" },
+	{ GPRS_UPD_T_RA_LA,		"combined RA/LA updating" },
+	{ GPRS_UPD_T_RA_LA_IMSI_ATT,	"combined RA/LA updating + IMSI attach" },
+	{ GPRS_UPD_T_PERIODIC,		"periodic updating" },
+	{ 0, NULL }
+};
+
+/* 10.5.5.5 */
+const struct value_string gprs_det_t_mo_strs[] = {
+	{ GPRS_DET_T_MO_GPRS,		"GPRS detach" },
+	{ GPRS_DET_T_MO_IMSI,		"IMSI detach" },
+	{ GPRS_DET_T_MO_COMBINED,	"Combined GPRS/IMSI detach" },
+	{ 0, NULL }
+};
+
+/* Our implementation, should be kept in SGSN */
 
 /* Send a message through the underlying layer */
 static int gsm48_gmm_sendmsg(struct msgb *msg, int command)
@@ -215,6 +214,22 @@
 	return gsm48_gmm_sendmsg(msg, 0);
 }
 
+/* Chapter 9.4.6.2 Detach accept */
+static gsm48_tx_gmm_det_ack(struct msgb *old_msg, uint8_t force_stby)
+{
+	struct msgb *msg = gsm48_msgb_alloc();
+	struct gsm48_hdr *gh;
+
+	DEBUGP(DMM, "<- GPRS DETACH ACCEPT\n");
+
+	gh = (struct gsm48_hdr *) msgb_put(msg, sizeof(*gh) + 1);
+	gh->proto_discr = GSM48_PDISC_MM_GPRS;
+	gh->msg_type = GSM48_MT_GMM_DETACH_ACK;
+	gh->data[0] = force_stby;
+
+	return gsm48_gmm_sendmsg(msg, 0);
+}
+
 /* Transmit Chapter 9.4.12 Identity Request */
 static int gsm48_tx_gmm_id_req(struct msgb *old_msg, uint8_t id_type)
 {
@@ -260,7 +275,7 @@
 	struct sgsn_mm_ctx *ctx;
 
 	gsm48_mi_to_string(mi_string, sizeof(mi_string), &gh->data[1], gh->data[0]);
-	DEBUGP(DMM, "GMM IDENTITY RESPONSE: mi_type=0x%02x MI(%s) ",
+	DEBUGP(DMM, "-> GMM IDENTITY RESPONSE: mi_type=0x%02x MI(%s) ",
 		mi_type, mi_string);
 
 	bssgp_parse_cell_id(&ra_id, msgb_bcid(msg));
@@ -320,7 +335,7 @@
 	uint16_t cid;
 	struct sgsn_mm_ctx *ctx;
 
-	DEBUGP(DMM, "GMM ATTACH REQUEST ");
+	DEBUGP(DMM, "-> GMM ATTACH REQUEST ");
 
 	/* As per TS 04.08 Chapter 4.7.1.4, the attach request arrives either
 	 * with a foreign TLLI (P-TMSI that was allocated to the MS before),
@@ -352,7 +367,8 @@
 
 	gsm48_mi_to_string(mi_string, sizeof(mi_string), mi, mi_len);
 
-	DEBUGPC(DMM, "MI(%s) type=\"%s\" ", mi_string, att_name(att_type));
+	DEBUGPC(DMM, "MI(%s) type=\"%s\" ", mi_string,
+		get_value_string(gprs_att_t_strs, att_type));
 
 	/* Old routing area identification 10.5.5.15 */
 	old_ra_info = cur;
@@ -411,6 +427,38 @@
 	return gsm48_tx_gmm_att_rej(msg, GMM_CAUSE_SEM_INCORR_MSG);
 }
 
+/* Section 4.7.4.1 / 9.4.5.2 MO Detach request */
+static int gsm48_rx_gmm_det_req(struct msgb *msg)
+{
+	struct gsm48_hdr *gh = (struct gsm48_hdr *) msgb_gmmh(msg);
+	struct sgsn_mm_ctx *ctx;
+	uint8_t detach_type, power_off;
+	struct gprs_ra_id ra_id;
+
+	bssgp_parse_cell_id(&ra_id, msgb_bcid(msg));
+	ctx = sgsn_mm_ctx_by_tlli(msgb_tlli(msg), &ra_id);
+	if (!ctx) {
+		LOGP(DMM, LOGL_NOTICE, "-> GMM DETACH REQUEST for unknown "
+			"TLLI=0x%08x\n", msgb_tlli(msg));
+		/* FIXME: send detach reject */
+	}
+
+	detach_type = gh->data[0] & 0x7;
+	power_off = gh->data[0] & 0x8;
+
+	/* FIXME: In 24.008 there is an optional P-TMSI and P-TMSI signature IE */
+
+	DEBUGP(DMM, "-> GMM DETACH REQUEST TLLI=0x%08x type=%s %s\n",
+		msgb_tlli(msg), get_value_string(gprs_det_t_mo_strs, detach_type),
+		power_off ? "Power-off" : "");
+
+	/* Mark MM state as deregistered */
+	ctx->mm_state = GMM_DEREGISTERED;
+
+	/* force_stby = 0 */
+	return gsm48_tx_gmm_det_ack(msg, 0);
+}
+
 /* Chapter 9.4.15: Routing area update accept */
 static int gsm48_tx_gmm_ra_upd_ack(struct msgb *old_msg)
 {
@@ -471,7 +519,8 @@
 	/* Update Type 10.5.5.18 */
 	upd_type = *cur++ & 0x0f;
 
-	DEBUGP(DMM, "GMM RA UPDATE REQUEST type=\"%s\" ", upd_name(upd_type));
+	DEBUGP(DMM, "-> GMM RA UPDATE REQUEST type=\"%s\" ",
+		get_value_string(gprs_upd_t_strs, upd_type));
 
 	/* Old routing area identification 10.5.5.15 */
 	gsm48_parse_ra(&old_ra_id, cur);
@@ -516,7 +565,7 @@
 {
 	struct gsm48_hdr *gh = msgb_l3(msg);
 
-	DEBUGP(DMM, "GPRS MM STATUS (cause: %s)\n",
+	DEBUGP(DMM, "-> GPRS MM STATUS (cause: %s)\n",
 		get_value_string(gmm_cause_names, gh->data[0]));
 
 	return 0;
@@ -541,19 +590,23 @@
 	case GSM48_MT_GMM_STATUS:
 		rc = gsm48_rx_gmm_status(msg);
 		break;
+	case GSM48_MT_GMM_DETACH_REQ:
+		rc = gsm48_rx_gmm_det_req(msg);
+		break;
 	case GSM48_MT_GMM_RA_UPD_COMPL:
 		/* only in case SGSN offered new P-TMSI */
 	case GSM48_MT_GMM_ATTACH_COMPL:
 		/* only in case SGSN offered new P-TMSI */
-	case GSM48_MT_GMM_DETACH_REQ:
 	case GSM48_MT_GMM_PTMSI_REALL_COMPL:
 	case GSM48_MT_GMM_AUTH_CIPH_RESP:
 		DEBUGP(DMM, "Unimplemented GSM 04.08 GMM msg type 0x%02x\n",
 			gh->msg_type);
+		/* FIXME: Send GMM_CAUSE_MSGT_NOTEXIST_NOTIMPL */
 		break;
 	default:
 		DEBUGP(DMM, "Unknown GSM 04.08 GMM msg type 0x%02x\n",
 			gh->msg_type);
+		/* FIXME: Send GMM_CAUSE_MSGT_NOTEXIST_NOTIMPL */
 		break;
 	}
 
@@ -641,7 +694,7 @@
 	uint8_t *req_qos, *req_pdpa;
 	struct tlv_parsed tp;
 
-	DEBUGP(DMM, "ACTIVATE PDP CONTEXT REQ: ");
+	DEBUGP(DMM, "-> ACTIVATE PDP CONTEXT REQ: ");
 	req_qos_len = act_req->data[0];
 	req_qos = act_req->data + 1;	/* 10.5.6.5 */
 	req_pdpa_len = act_req->data[1 + req_qos_len];
@@ -679,11 +732,22 @@
 		break;
 	}
 
+	/* put the non-TLV elements in the TLV parser structure to
+	 * pass them on to the SGSN / GTP code */
+	tp.lv[OSMO_IE_GSM_REQ_QOS].len = req_qos_len;
+	tp.lv[OSMO_IE_GSM_REQ_QOS].val = req_qos;
+	tp.lv[OSMO_IE_GSM_REQ_PDP_ADDR].len = req_pdpa_len;
+	tp.lv[OSMO_IE_GSM_REQ_PDP_ADDR].val = req_pdpa;
+
 	/* FIXME: parse TLV for AP name and protocol config options */
 	if (TLVP_PRESENT(&tp, GSM48_IE_GSM_APN)) {}
 	if (TLVP_PRESENT(&tp, GSM48_IE_GSM_PROTO_CONF_OPT)) {}
 
+#if 0
+	return sgsn_create_pdp_ctx(ggsn, &tp);
+#else
 	return gsm48_tx_gsm_act_pdp_acc(msg, act_req);
+#endif
 }
 
 /* Section 9.5.8: Deactivate PDP Context Request */
@@ -691,7 +755,7 @@
 {
 	struct gsm48_hdr *gh = (struct gsm48_hdr *) msgb_gmmh(msg);
 
-	DEBUGP(DMM, "DEACTIVATE PDP CONTEXT REQ (cause: %s)\n",
+	DEBUGP(DMM, "-> DEACTIVATE PDP CONTEXT REQ (cause: %s)\n",
 		get_value_string(gsm_cause_names, gh->data[0]));
 
 	return gsm48_tx_gsm_deact_pdp_acc(msg);
@@ -701,7 +765,7 @@
 {
 	struct gsm48_hdr *gh = msgb_l3(msg);
 
-	DEBUGP(DMM, "GPRS SM STATUS (cause: %s)\n",
+	DEBUGP(DMM, "-> GPRS SM STATUS (cause: %s)\n",
 		get_value_string(gsm_cause_names, gh->data[0]));
 
 	return 0;
diff --git a/openbsc/src/gprs/gprs_sgsn.c b/openbsc/src/gprs/gprs_sgsn.c
index ba46719..90ede76 100644
--- a/openbsc/src/gprs/gprs_sgsn.c
+++ b/openbsc/src/gprs/gprs_sgsn.c
@@ -81,8 +81,9 @@
 struct sgsn_mm_ctx *sgsn_mm_ctx_alloc(uint32_t tlli,
 					const struct gprs_ra_id *raid)
 {
-	struct sgsn_mm_ctx *ctx = talloc_zero(NULL, struct sgsn_mm_ctx);
+	struct sgsn_mm_ctx *ctx;
 
+	ctx = talloc_zero(tall_bsc_ctx, struct sgsn_mm_ctx);
 	if (!ctx)
 		return NULL;
 
diff --git a/openbsc/src/gprs/gprs_sndcp.c b/openbsc/src/gprs/gprs_sndcp.c
index 0d1a390..99a7638 100644
--- a/openbsc/src/gprs/gprs_sndcp.c
+++ b/openbsc/src/gprs/gprs_sndcp.c
@@ -54,6 +54,9 @@
 	uint8_t npdu_low;
 };
 
+struct sndcp_entity {
+};
+
 /* Entry point for the LL-UNITDATA.indication */
 int sndcp_unitdata_ind(struct msgb *msg, uint8_t sapi, uint8_t *hdr, uint8_t len)
 {
@@ -68,3 +71,59 @@
 	npdu = (suh->npdu_high << 8) | suh->npdu_low;
 }
 
+/* Section 5.1.2.1 LL-RESET.ind */
+static int sndcp_ll_reset_ind(struct sndcp_entity *se,)
+{
+	/* treat all outstanding SNDCP-LLC request type primitives as not sent */
+	/* reset all SNDCP XID parameters to default values */
+}
+
+/* Section 5.1.2.17 LL-UNITDATA.ind */
+static int sndcp_ll_unitdata_ind()
+{
+}
+
+static int sndcp_ll_status_ind()
+{
+	/* inform the SM sub-layer by means of SNSM-STATUS.req */
+}
+
+static struct sndcp_state_list {{
+	uint32_t	states;
+	unsigned int	type;
+	int		(*rout)(struct sndcp_entity *se, struct msgb *msg);
+} sndcp_state_list[] = {
+	{ ALL_STATES,
+	  LL_RESET_IND, sndcp_ll_reset_ind },
+	{ ALL_STATES,
+	  LL_ESTABLISH_IND, sndcp_ll_est_ind },
+	{ SBIT(SNDCP_S_EST_RQD),
+	  LL_ESTABLISH_RESP, sndcp_ll_est_ind },
+	{ SBIT(SNDCP_S_EST_RQD),
+	  LL_ESTABLISH_CONF, sndcp_ll_est_conf },
+	{ SBIT(SNDCP_S_
+};
+
+static int sndcp_rx_llc_prim()
+{
+	case LL_ESTABLISH_REQ:
+	case LL_RELEASE_REQ:
+	case LL_XID_REQ:
+	case LL_DATA_REQ:
+	LL_UNITDATA_REQ,	/* TLLI, SN-PDU, Ref, QoS, Radio Prio, Ciph */
+
+	switch (prim) {
+	case LL_RESET_IND:
+	case LL_ESTABLISH_IND:
+	case LL_ESTABLISH_RESP:
+	case LL_ESTABLISH_CONF:
+	case LL_RELEASE_IND:
+	case LL_RELEASE_CONF:
+	case LL_XID_IND:
+	case LL_XID_RESP:
+	case LL_XID_CONF:
+	case LL_DATA_IND:
+	case LL_DATA_CONF:
+	case LL_UNITDATA_IND:
+	case LL_STATUS_IND:
+}
diff --git a/openbsc/src/gprs/sgsn_libgtp.c b/openbsc/src/gprs/sgsn_libgtp.c
new file mode 100644
index 0000000..fcaee8b
--- /dev/null
+++ b/openbsc/src/gprs/sgsn_libgtp.c
@@ -0,0 +1,421 @@
+/* GPRS SGSN integration with libgtp of OpenGGSN */
+
+/* (C) 2010 by Harald Welte <laforge@gnumonks.org>
+ * (C) 2010 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 General Public License as published by
+ * the Free Software Foundation; either version 2 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ */
+
+#include <unistd.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <getopt.h>
+#include <errno.h>
+#include <signal.h>
+#include <sys/fcntl.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+
+#include <osmocore/talloc.h>
+#include <osmocore/select.h>
+#include <osmocore/rate_ctr.h>
+
+#include <openbsc/signal.h>
+#include <openbsc/debug.h>
+#include <openbsc/sgsn.h>
+//#include <openbsc/gprs_ns.h>
+//#include <openbsc/gprs_bssgp.h>
+#include <openbsc/gprs_sgsn.h>
+#include <openbsc/gsm_04_08_gprs.h>
+
+#include <gtp.h>
+#include <pdp.h>
+
+struct ggsn_ctx {
+	unsigned int gtp_version;
+	struct in_addr remote_addr;
+	struct gsn_t *gsn;
+};
+
+const struct value_string gtp_cause_strs[] = {
+	{ GTPCAUSE_REQ_IMSI, "Request IMSI" },
+	{ GTPCAUSE_REQ_IMEI, "Request IMEI" },
+	{ GTPCAUSE_REQ_IMSI_IMEI, "Request IMSI and IMEI" },
+	{ GTPCAUSE_NO_ID_NEEDED, "No identity needed" },
+	{ GTPCAUSE_MS_REFUSES_X, "MS refuses" },
+	{ GTPCAUSE_MS_NOT_RESP_X, "MS is not GPRS responding" },
+	{ GTPCAUSE_ACC_REQ, "Request accepted" },
+	{ GTPCAUSE_NON_EXIST, "Non-existent" },
+	{ GTPCAUSE_INVALID_MESSAGE, "Invalid message format" },
+	{ GTPCAUSE_IMSI_NOT_KNOWN, "IMSI not known" },
+	{ GTPCAUSE_MS_DETACHED, "MS is GPRS detached" },
+	{ GTPCAUSE_MS_NOT_RESP, "MS is not GPRS responding" },
+	{ GTPCAUSE_MS_REFUSES, "MS refuses" },
+	{ GTPCAUSE_NO_RESOURCES, "No resources available" },
+	{ GTPCAUSE_NOT_SUPPORTED, "Service not supported" },
+	{ GTPCAUSE_MAN_IE_INCORRECT, "Mandatory IE incorrect" },
+	{ GTPCAUSE_MAN_IE_MISSING, "Mandatory IE missing" },
+	{ GTPCAUSE_OPT_IE_INCORRECT, "Optional IE incorrect" },
+	{ GTPCAUSE_SYS_FAIL, "System failure" },
+	{ GTPCAUSE_ROAMING_REST, "Roaming restrictions" },
+	{ GTPCAUSE_PTIMSI_MISMATCH, "P-TMSI Signature mismatch" },
+	{ GTPCAUSE_CONN_SUSP, "GPRS connection suspended" },
+	{ GTPCAUSE_AUTH_FAIL, "Authentication failure" },
+	{ GTPCAUSE_USER_AUTH_FAIL, "User authentication failed" },
+	{ GTPCAUSE_CONTEXT_NOT_FOUND, "Context not found" },
+	{ GTPCAUSE_ADDR_OCCUPIED, "All dynamic PDP addresses occupied" },
+	{ GTPCAUSE_NO_MEMORY, "No memory is available" },
+	{ GTPCAUSE_RELOC_FAIL, "Relocation failure" },
+	{ GTPCAUSE_UNKNOWN_MAN_EXTHEADER, "Unknown mandatory ext. header" },
+	{ GTPCAUSE_SEM_ERR_TFT, "Semantic error in TFT operation" },
+	{ GTPCAUSE_SYN_ERR_TFT, "Syntactic error in TFT operation" },
+	{ GTPCAUSE_SEM_ERR_FILTER, "Semantic errors in packet filter" },
+	{ GTPCAUSE_SYN_ERR_FILTER, "Syntactic errors in packet filter" },
+	{ GTPCAUSE_MISSING_APN, "Missing or unknown APN" },
+	{ GTPCAUSE_UNKNOWN_PDP, "Unknown PDP address or PDP type" },
+	{ 0, NULL }
+};
+
+/* generate a PDP context based on the IE's from the 04.08 message,
+ * and send the GTP create pdp context request to the GGSN */
+int sgsn_create_pdp_ctx(struct ggsn_ctx *ggsn, struct sgsn_mm_ctx *mmctx,
+			uint16_t nsapi, struct tlv_parsed *tp)
+{
+	struct sgsn_instance *sgsn = mmctx->sgsn;
+	struct pdp_t *pdp;
+	uint64_t imsi_ui64;
+	int rc;
+
+	rc = pdp_newpdp(&pdp, imsi_ui64, nsapi, NULL);
+	if (rc) {
+		LOGP(DGPRS, LOGL_ERROR, "Out of PDP Contexts\n");
+		return -ENOMEM;
+	}
+	//pdp->peer =	/* sockaddr_in of GGSN (receive) */
+	//pdp->ipif =	/* not used by library */
+	pdp->version = ggsn->gtp_version;
+	pdp->hisaddr0 =	ggsn->remote_addr;
+	pdp->hisaddr1 = ggsn->remote_addr;
+	//pdp->cch_pdp = 512;	/* Charging Flat Rate */
+
+	/* MS provided APN, subscription not verified */
+	pdp->selmode = 0x01;
+
+	/* IMSI, TEID/TEIC, FLLU/FLLC, TID, NSAPI set in pdp_newpdp */
+
+	/* FIXME: MSISDN in BCD format from mmctx */
+	//pdp->msisdn.l/.v
+
+	/* End User Address from GMM requested PDP address */
+	pdp->eua.l = TLVP_LEN(tp, OSMO_IE_GSM_REQ_PDP_ADDR);
+	if (pdp->eua.l > sizeof(pdp->eua.v))
+		pdp->eua.l = sizeof(pdp->eua.v);
+	memcpy(pdp->eua.v, TLVP_VAL(tp, OSMO_IE_GSM_REQ_PDP_ADDR),
+		pdp->eua.l);
+	/* Highest 4 bits of first byte need to be set to 1, otherwise
+	 * the IE is identical with the 04.08 PDP Address IE */
+	pdp->eua.v[0] |= 0xf0;
+
+	/* APN name from GMM */
+	pdp->apn_use.l = TLVP_LEN(tp, GSM48_IE_GSM_APN);
+	if (pdp->apn_use.l > sizeof(pdp->apn_use.v))
+		pdp->apn_use.l = sizeof(pdp->apn_use.v);
+	memcpy(pdp->apn_use.v, TLVP_VAL(tp, GSM48_IE_GSM_APN),
+		pdp->apn_use.l);
+
+	/* Protocol Configuration Options from GMM */
+	pdp->pco_req.l = TLVP_LEN(tp, GSM48_IE_GSM_PROTO_CONF_OPT);
+	if (pdp->pco_req.l > sizeof(pdp->pco_req.v))
+		pdp->pco_req.l = sizeof(pdp->pco_req.v);
+	memcpy(pdp->pco_req.v, TLVP_VAL(tp, GSM48_IE_GSM_PROTO_CONF_OPT),
+		pdp->pco_req.l);
+
+	/* QoS options from GMM */
+	pdp->qos_req.l = TLVP_LEN(tp, OSMO_IE_GSM_REQ_QOS);
+	if (pdp->qos_req.l > sizeof(pdp->qos_req.v))
+		pdp->qos_req.l = sizeof(pdp->qos_req.v);
+	memcpy(pdp->qos_req.v, TLVP_VAL(tp, OSMO_IE_GSM_REQ_QOS),
+		pdp->qos_req.l);
+
+	/* SGSN address for control plane */
+	pdp->gsnlc.l = sizeof(sgsn->cfg.gtp_listenaddr);
+	memcpy(pdp->gsnlc.v, &sgsn->cfg.gtp_listenaddr,
+		sizeof(sgsn->cfg.gtp_listenaddr));
+
+	/* SGSN address for user plane */
+	pdp->gsnlu.l = sizeof(sgsn->cfg.gtp_listenaddr);
+	memcpy(pdp->gsnlu.v, &sgsn->cfg.gtp_listenaddr,
+		sizeof(sgsn->cfg.gtp_listenaddr));
+
+	/* FIXME: change pdp state to 'requested' */
+
+	/* FIXME: pass along a pointer to the MM CTX */
+	return gtp_create_context_req(ggsn->gsn, pdp, mmctx);
+}
+
+/* The GGSN has confirmed the creation of a PDP Context */
+static int create_pdp_conf(struct pdp_t *pdp, void *cbp, int cause)
+{
+	struct sgsn_mm_ctx *mmctx = cbp;
+
+	DEBUGP(DGPRS, "Received CREATE PDP CTX CONF, cause=%d(%s)\n",
+		cause, get_value_string(gtp_cause_strs, cause));
+
+	/* Check for cause value if it was really successful */
+	if (cause < 0) {
+		LOGP(DGPRS, LOGL_NOTICE, "Create PDP ctx req timed out\n");
+		if (pdp->version == 1) {
+			pdp->version = 0;
+			gtp_create_context_req(mmctx->sgsn->gsn, pdp, cbp);
+			return 0;
+		} else {
+			pdp_freepdp(pdp);
+			return EOF;
+		}
+	}
+
+	/* Check for cause value if it was really successful */
+	if (cause != GTPCAUSE_ACC_REQ) {
+		pdp_freepdp(pdp);
+		return EOF;
+	}
+
+	/* FIXME: Determine MM ctx for the PDP ctx */
+	/* FIXME: Send PDP CTX ACT ACK/REJ to MS */
+	return 0;
+}
+
+/* If we receive a 04.08 DEACT PDP CTX REQ or GPRS DETACH, we need to
+ * look-up the PDP context and request its deletion from the SGSN */
+int sgsn_delete_pdp_ctx(struct ggsn_ctx *ggsn, struct sgsn_mm_ctx *mmctx,
+			struct tlv_parsed *tp)
+{
+	//return gtp_delete_context_req(gsn, pdp, cbp, teardown);
+}
+
+/* Confirmation of a PDP Context Delete */
+static int delete_pdp_conf(struct pdp_t *pdp, int cause)
+{
+	DEBUGP(DGPRS, "Received DELETE PDP CTX CONF, cause=%d(%s)\n",
+		cause, get_value_string(gtp_cause_strs, cause));
+	return 0;
+}
+
+/* Confirmation of an GTP ECHO request */
+static int echo_conf(int recovery)
+{
+	if (recovery < 0) {
+		DEBUGP(DGPRS, "GTP Echo Request timed out\n");
+		/* FIXME: if version == 1, retry with version 0 */
+	} else {
+		DEBUGP(DGPRS, "GTP Rx Echo Response\n");
+	}
+	return 0;
+}
+
+/* libgtp callback for confirmations */
+static int cb_conf(int type, int cause, struct pdp_t *pdp, void *cbp)
+{
+	DEBUGP(DGPRS, "libgtp cb_conf(type=%d, cause=%d, pdp=%p, cbp=%p)\n",
+		type, cause, pdp, cbp);
+
+	if (cause == EOF)
+		LOGP(DGPRS, LOGL_ERROR, "libgtp EOF (type=%u, pdp=%p, cbp=%p)\n",
+			type, pdp, cbp);
+
+	switch (type) {
+	case GTP_ECHO_REQ:
+		return echo_conf(cause);
+	case GTP_CREATE_PDP_REQ:
+		return create_pdp_conf(pdp, cbp, cause);
+	case GTP_DELETE_PDP_REQ:
+		return delete_pdp_conf(pdp, cause);
+	default:
+		break;
+	}
+	return 0;
+}
+
+/* Called whenever a PDP context is deleted for any reason */
+static int cb_delete_context(struct pdp_t *pdp)
+{
+	LOGP(DGPRS, LOGL_INFO, "PDP Context was deleted\n");
+	return 0;
+}
+
+/* Called when we receive a Version Not Supported message */
+static int cb_unsup_ind(struct sockaddr_in *peer)
+{
+	LOGP(DGPRS, LOGL_INFO, "GTP Version not supported Indication "
+		"from %s:%u\n", inet_ntoa(peer->sin_addr),
+		ntohs(peer->sin_port));
+	return 0;
+}
+
+/* Called when we receive a Supported Ext Headers Notification */
+static int cb_extheader_ind(struct sockaddr_in *peer)
+{
+	LOGP(DGPRS, LOGL_INFO, "GTP Supported Ext Headers Noficiation "
+		"from %s:%u\n", inet_ntoa(peer->sin_addr),
+		ntohs(peer->sin_port));
+	return 0;
+}
+
+/* Called whenever we recive a DATA packet */
+static int cb_data_ind(struct pdp_t *pdp, void *packet, unsigned int len)
+{
+	DEBUGP(DGPRS, "GTP DATA IND from GGSN, length=%u\n", len);
+
+	return 0;
+}
+
+/* libgtp select loop integration */
+static int sgsn_gtp_fd_cb(struct bsc_fd *fd, unsigned int what)
+{
+	struct sgsn_instance *sgi = fd->data;
+	int rc;
+
+	if (!(what & BSC_FD_READ))
+		return 0;
+
+	switch (fd->priv_nr) {
+	case 0:
+		rc = gtp_decaps0(sgi->gsn);
+		break;
+	case 1:
+		rc = gtp_decaps1c(sgi->gsn);
+		break;
+	case 2:
+		rc = gtp_decaps1u(sgi->gsn);
+		break;
+	}
+	return rc;
+}
+
+static void timeval_normalize(struct timeval *tv)
+{
+	unsigned int sec = tv->tv_usec / 1000000;
+	tv->tv_sec += sec;
+	tv->tv_usec -= sec * 1000000;
+}
+
+/* diff = a - b */
+static int timeval_diff(struct timeval *diff,
+			struct timeval *a,
+			struct timeval *b)
+{
+	/* Step 1: normalize input values */
+	timeval_normalize(a);
+	timeval_normalize(b);
+
+	if (b->tv_sec > a->tv_sec ||
+	    b->tv_sec == a->tv_sec && b->tv_usec > a->tv_usec) {
+		b->tv_sec = b->tv_usec = 0;
+		return -ERANGE;
+	}
+
+	if (b->tv_usec > a->tv_usec) {
+		a->tv_sec -= 1;
+		a->tv_usec += 1000000;
+	}
+
+	diff->tv_usec = a->tv_usec - b->tv_usec;
+	diff->tv_sec = a->tv_sec - b->tv_sec;
+
+	return 0;
+}
+
+static void sgsn_gtp_tmr_start(struct sgsn_instance *sgi)
+{
+	struct timeval now, next, diff;
+
+	/* Retrieve next retransmission as struct timeval */
+	gtp_retranstimeout(sgi->gsn, &next);
+
+	/* Calculate the difference to now */
+	gettimeofday(&now, NULL);
+	timeval_diff(&diff, &next, &now);
+
+	/* re-schedule the timer */
+	bsc_schedule_timer(&sgi->gtp_timer, diff.tv_sec, diff.tv_usec/1000);
+}
+
+/* timer callback for libgtp retransmissions and ping */
+static void sgsn_gtp_tmr_cb(void *data)
+{
+	struct sgsn_instance *sgi = data;
+
+	/* Do all the retransmissions as needed */
+	gtp_retrans(sgi->gsn);
+
+	sgsn_gtp_tmr_start(sgi);
+}
+
+int sgsn_gtp_init(struct sgsn_instance *sgi)
+{
+	int rc;
+	struct gsn_t *gsn;
+
+	rc = gtp_new(&sgi->gsn, sgi->cfg.gtp_statedir,
+		     &sgi->cfg.gtp_listenaddr.sin_addr, GTP_MODE_SGSN);
+	if (rc) {
+		LOGP(DGPRS, LOGL_ERROR, "Failed to create GTP: %d\n", rc);
+		return rc;
+	}
+	gsn = sgi->gsn;
+
+	sgi->gtp_fd0.fd = gsn->fd0;
+	sgi->gtp_fd0.priv_nr = 0;
+	sgi->gtp_fd0.data = sgi;
+	sgi->gtp_fd0.cb = sgsn_gtp_fd_cb;
+	rc = bsc_register_fd(&sgi->gtp_fd0);
+	if (rc < 0)
+		return rc;
+
+	sgi->gtp_fd1c.fd = gsn->fd1c;
+	sgi->gtp_fd1c.priv_nr = 1;
+	sgi->gtp_fd1c.data = sgi;
+	sgi->gtp_fd1c.cb = sgsn_gtp_fd_cb;
+	bsc_register_fd(&sgi->gtp_fd1c);
+	if (rc < 0)
+		return rc;
+
+	sgi->gtp_fd1u.fd = gsn->fd1u;
+	sgi->gtp_fd1u.priv_nr = 2;
+	sgi->gtp_fd1u.data = sgi;
+	sgi->gtp_fd1u.cb = sgsn_gtp_fd_cb;
+	bsc_register_fd(&sgi->gtp_fd1u);
+	if (rc < 0)
+		return rc;
+
+	/* Start GTP re-transmission timer */
+	sgi->gtp_timer.cb = sgsn_gtp_tmr_cb;
+	sgsn_gtp_tmr_start(sgi);
+
+	/* Register callbackcs with libgtp */
+	gtp_set_cb_delete_context(gsn, cb_delete_context);
+	gtp_set_cb_conf(gsn, cb_conf);
+	gtp_set_cb_data_ind(gsn, cb_data_ind);
+	gtp_set_cb_unsup_ind(gsn, cb_unsup_ind);
+	gtp_set_cb_extheader_ind(gsn, cb_extheader_ind);
+
+	return 0;
+}
diff --git a/openbsc/src/gprs/sgsn_main.c b/openbsc/src/gprs/sgsn_main.c
index 7aa6e13..ac895a2 100644
--- a/openbsc/src/gprs/sgsn_main.c
+++ b/openbsc/src/gprs/sgsn_main.c
@@ -46,6 +46,8 @@
 #include <openbsc/gprs_ns.h>
 #include <openbsc/gprs_bssgp.h>
 
+#include <gtp.h>
+
 #include "../../bscconfig.h"
 
 /* this is here for the vty... it will never be called */
@@ -64,8 +66,12 @@
 	"This is free software: you are free to change and redistribute it.\n"
 	"There is NO WARRANTY, to the extent permitted by law.\n";
 
-static char *config_file = "osmo_sgsn.cfg";
-static struct sgsn_config sgcfg;
+struct sgsn_instance sgsn_inst = {
+	.config_file = "osmo_sgsn.cfg",
+	.cfg = {
+		.gtp_statedir = "./",
+	},
+};
 
 /* call-back function for the NS protocol */
 static int sgsn_ns_cb(enum gprs_ns_evt event, struct gprs_nsvc *nsvc,
@@ -152,17 +158,18 @@
 		LOGP(DGPRS, LOGL_ERROR, "Unable to instantiate NS\n");
 		exit(1);
 	}
-	bssgp_nsi = sgcfg.nsi = sgsn_nsi;
+	bssgp_nsi = sgsn_inst.cfg.nsi = sgsn_nsi;
 	gprs_ns_vty_init(bssgp_nsi);
 	/* FIXME: register signal handler for SS_NS */
 
-	rc = sgsn_parse_config(config_file, &sgcfg);
+	rc = sgsn_parse_config(sgsn_inst.config_file, &sgsn_inst.cfg);
 	if (rc < 0) {
 		LOGP(DGPRS, LOGL_FATAL, "Cannot parse config file\n");
 		exit(2);
 	}
 
-	nsip_listen(sgsn_nsi, sgcfg.nsip_listen_port);
+	rc = sgsn_gtp_init(&sgsn_inst);
+	nsip_listen(sgsn_nsi, sgsn_inst.cfg.nsip_listen_port);
 
 	while (1) {
 		rc = bsc_select_main(0);