diff --git a/openbsc/src/libcommon/Makefile.am b/openbsc/src/libcommon/Makefile.am
index 6582d1e..0b258c0 100644
--- a/openbsc/src/libcommon/Makefile.am
+++ b/openbsc/src/libcommon/Makefile.am
@@ -23,8 +23,25 @@
 	debug.c \
 	gsm_data.c \
 	gsm_data_shared.c \
+	gsup_client.c \
 	oap_client.c \
 	socket.c \
 	talloc_ctx.c \
 	gsm_subscriber_base.c \
 	$(NULL)
+
+noinst_PROGRAMS = \
+	gsup_test_client \
+	$(NULL)
+
+gsup_test_client_SOURCES = \
+	gsup_test_client.c \
+	$(NULL)
+gsup_test_client_LDADD = \
+	libcommon.a \
+	$(LIBOSMOCORE_LIBS) \
+	$(LIBOSMOGSM_LIBS) \
+	$(LIBOSMOVTY_LIBS) \
+	$(LIBOSMOABIS_LIBS) \
+	-lrt \
+	$(NULL)
diff --git a/openbsc/src/libcommon/gsup_client.c b/openbsc/src/libcommon/gsup_client.c
new file mode 100644
index 0000000..0360e0a
--- /dev/null
+++ b/openbsc/src/libcommon/gsup_client.c
@@ -0,0 +1,341 @@
+/* Generic Subscriber Update Protocol client */
+
+/* (C) 2014-2016 by Sysmocom s.f.m.c. GmbH
+ * All Rights Reserved
+ *
+ * Author: Jacob Erlbeck
+ * Author: Neels Hofmeyr
+ *
+ * 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/gsup_client.h>
+
+#include <osmocom/abis/ipa.h>
+#include <osmocom/gsm/protocol/ipaccess.h>
+#include <osmocom/core/msgb.h>
+#include <osmocom/core/logging.h>
+
+#include <openbsc/debug.h>
+
+#include <errno.h>
+#include <string.h>
+
+extern void *tall_bsc_ctx;
+
+static void start_test_procedure(struct gsup_client *gsupc);
+
+static void gsup_client_send_ping(struct gsup_client *gsupc)
+{
+	struct msgb *msg = gsup_client_msgb_alloc();
+
+	msg->l2h = msgb_put(msg, 1);
+	msg->l2h[0] = IPAC_MSGT_PING;
+	ipa_msg_push_header(msg, IPAC_PROTO_IPACCESS);
+	ipa_client_conn_send(gsupc->link, msg);
+}
+
+static int gsup_client_connect(struct gsup_client *gsupc)
+{
+	int rc;
+
+	if (gsupc->is_connected)
+		return 0;
+
+	if (osmo_timer_pending(&gsupc->connect_timer)) {
+		LOGP(DLGSUP, LOGL_DEBUG,
+		     "GSUP connect: connect timer already running\n");
+		osmo_timer_del(&gsupc->connect_timer);
+	}
+
+	if (osmo_timer_pending(&gsupc->ping_timer)) {
+		LOGP(DLGSUP, LOGL_DEBUG,
+		     "GSUP connect: ping timer already running\n");
+		osmo_timer_del(&gsupc->ping_timer);
+	}
+
+	if (ipa_client_conn_clear_queue(gsupc->link) > 0)
+		LOGP(DLGSUP, LOGL_DEBUG, "GSUP connect: discarded stored messages\n");
+
+	rc = ipa_client_conn_open(gsupc->link);
+
+	if (rc >= 0) {
+		LOGP(DLGSUP, LOGL_INFO, "GSUP connecting to %s:%d\n",
+		     gsupc->link->addr, gsupc->link->port);
+		return 0;
+	}
+
+	LOGP(DLGSUP, LOGL_INFO, "GSUP failed to connect to %s:%d: %s\n",
+	     gsupc->link->addr, gsupc->link->port, strerror(-rc));
+
+	if (rc == -EBADF || rc == -ENOTSOCK || rc == -EAFNOSUPPORT ||
+	    rc == -EINVAL)
+		return rc;
+
+	osmo_timer_schedule(&gsupc->connect_timer,
+			    GSUP_CLIENT_RECONNECT_INTERVAL, 0);
+
+	LOGP(DLGSUP, LOGL_INFO, "Scheduled timer to retry GSUP connect to %s:%d\n",
+	     gsupc->link->addr, gsupc->link->port);
+
+	return 0;
+}
+
+static void connect_timer_cb(void *gsupc_)
+{
+	struct gsup_client *gsupc = gsupc_;
+
+	if (gsupc->is_connected)
+		return;
+
+	gsup_client_connect(gsupc);
+}
+
+static void client_send(struct gsup_client *gsupc, int proto_ext,
+			struct msgb *msg_tx)
+{
+	ipa_prepend_header_ext(msg_tx, proto_ext);
+	ipa_msg_push_header(msg_tx, IPAC_PROTO_OSMO);
+	ipa_client_conn_send(gsupc->link, msg_tx);
+	/* msg_tx is now queued and will be freed. */
+}
+
+static void gsup_client_oap_register(struct gsup_client *gsupc)
+{
+	struct msgb *msg_tx;
+	int rc;
+	rc = oap_client_register(&gsupc->oap_state, &msg_tx);
+
+	if ((rc < 0) || (!msg_tx)) {
+		LOGP(DLGSUP, LOGL_ERROR, "GSUP OAP set up, but cannot register.\n");
+		return;
+	}
+
+	client_send(gsupc, IPAC_PROTO_EXT_OAP, msg_tx);
+}
+
+static void gsup_client_updown_cb(struct ipa_client_conn *link, int up)
+{
+	struct gsup_client *gsupc = link->data;
+
+	LOGP(DLGSUP, LOGL_INFO, "GSUP link to %s:%d %s\n",
+		     link->addr, link->port, up ? "UP" : "DOWN");
+
+	gsupc->is_connected = up;
+
+	if (up) {
+		start_test_procedure(gsupc);
+
+		if (gsupc->oap_state.state == OAP_INITIALIZED)
+			gsup_client_oap_register(gsupc);
+
+		osmo_timer_del(&gsupc->connect_timer);
+	} else {
+		osmo_timer_del(&gsupc->ping_timer);
+
+		osmo_timer_schedule(&gsupc->connect_timer,
+				    GSUP_CLIENT_RECONNECT_INTERVAL, 0);
+	}
+}
+
+static int gsup_client_oap_handle(struct gsup_client *gsupc, struct msgb *msg_rx)
+{
+	int rc;
+	struct msgb *msg_tx;
+
+	rc = oap_client_handle(&gsupc->oap_state, msg_rx, &msg_tx);
+	msgb_free(msg_rx);
+	if (rc < 0)
+		return rc;
+
+	if (msg_tx)
+		client_send(gsupc, IPAC_PROTO_EXT_OAP, msg_tx);
+
+	return 0;
+}
+
+static int gsup_client_read_cb(struct ipa_client_conn *link, struct msgb *msg)
+{
+	struct ipaccess_head *hh = (struct ipaccess_head *) msg->data;
+	struct ipaccess_head_ext *he = (struct ipaccess_head_ext *) msgb_l2(msg);
+	struct gsup_client *gsupc = (struct gsup_client *)link->data;
+	int rc;
+	static struct ipaccess_unit ipa_dev = {
+		.unit_name = "SGSN"
+	};
+
+	msg->l2h = &hh->data[0];
+
+	rc = ipaccess_bts_handle_ccm(link, &ipa_dev, msg);
+
+	if (rc < 0) {
+		LOGP(DLGSUP, LOGL_NOTICE,
+		     "GSUP received an invalid IPA/CCM message from %s:%d\n",
+		     link->addr, link->port);
+		/* Link has been closed */
+		gsupc->is_connected = 0;
+		msgb_free(msg);
+		return -1;
+	}
+
+	if (rc == 1) {
+		uint8_t msg_type = *(msg->l2h);
+		/* CCM message */
+		if (msg_type == IPAC_MSGT_PONG) {
+			LOGP(DLGSUP, LOGL_DEBUG, "GSUP receiving PONG\n");
+			gsupc->got_ipa_pong = 1;
+		}
+
+		msgb_free(msg);
+		return 0;
+	}
+
+	if (hh->proto != IPAC_PROTO_OSMO)
+		goto invalid;
+
+	if (!he || msgb_l2len(msg) < sizeof(*he))
+		goto invalid;
+
+	msg->l2h = &he->data[0];
+
+	if (he->proto == IPAC_PROTO_EXT_GSUP) {
+		OSMO_ASSERT(gsupc->read_cb != NULL);
+		gsupc->read_cb(gsupc, msg);
+		/* expecting read_cb() to free msg */
+	} else if (he->proto == IPAC_PROTO_EXT_OAP) {
+		return gsup_client_oap_handle(gsupc, msg);
+		/* gsup_client_oap_handle frees msg */
+	} else
+		goto invalid;
+
+	return 0;
+
+invalid:
+	LOGP(DLGSUP, LOGL_NOTICE,
+	     "GSUP received an invalid IPA message from %s:%d, size = %d\n",
+	     link->addr, link->port, msgb_length(msg));
+
+	msgb_free(msg);
+	return -1;
+}
+
+static void ping_timer_cb(void *gsupc_)
+{
+	struct gsup_client *gsupc = gsupc_;
+
+	LOGP(DLGSUP, LOGL_INFO, "GSUP ping callback (%s, %s PONG)\n",
+	     gsupc->is_connected ? "connected" : "not connected",
+	     gsupc->got_ipa_pong ? "got" : "didn't get");
+
+	if (gsupc->got_ipa_pong) {
+		start_test_procedure(gsupc);
+		return;
+	}
+
+	LOGP(DLGSUP, LOGL_NOTICE, "GSUP ping timed out, reconnecting\n");
+	ipa_client_conn_close(gsupc->link);
+	gsupc->is_connected = 0;
+
+	gsup_client_connect(gsupc);
+}
+
+static void start_test_procedure(struct gsup_client *gsupc)
+{
+	gsupc->ping_timer.data = gsupc;
+	gsupc->ping_timer.cb = &ping_timer_cb;
+
+	gsupc->got_ipa_pong = 0;
+	osmo_timer_schedule(&gsupc->ping_timer, GSUP_CLIENT_PING_INTERVAL, 0);
+	LOGP(DLGSUP, LOGL_DEBUG, "GSUP sending PING\n");
+	gsup_client_send_ping(gsupc);
+}
+
+struct gsup_client *gsup_client_create(const char *ip_addr,
+				       unsigned int tcp_port,
+				       gsup_client_read_cb_t read_cb,
+				       struct oap_client_config *oap_config)
+{
+	struct gsup_client *gsupc;
+	int rc;
+
+	gsupc = talloc_zero(tall_bsc_ctx, struct gsup_client);
+	OSMO_ASSERT(gsupc);
+
+	rc = oap_client_init(oap_config, &gsupc->oap_state);
+	if (rc != 0)
+		goto failed;
+
+	gsupc->link = ipa_client_conn_create(gsupc,
+					     /* no e1inp */ NULL,
+					     0,
+					     ip_addr, tcp_port,
+					     gsup_client_updown_cb,
+					     gsup_client_read_cb,
+					     /* default write_cb */ NULL,
+					     gsupc);
+	if (!gsupc->link)
+		goto failed;
+
+	gsupc->connect_timer.data = gsupc;
+	gsupc->connect_timer.cb = &connect_timer_cb;
+
+	rc = gsup_client_connect(gsupc);
+
+	if (rc < 0)
+		goto failed;
+
+	gsupc->read_cb = read_cb;
+
+	return gsupc;
+
+failed:
+	gsup_client_destroy(gsupc);
+	return NULL;
+}
+
+void gsup_client_destroy(struct gsup_client *gsupc)
+{
+	osmo_timer_del(&gsupc->connect_timer);
+	osmo_timer_del(&gsupc->ping_timer);
+
+	if (gsupc->link) {
+		ipa_client_conn_close(gsupc->link);
+		ipa_client_conn_destroy(gsupc->link);
+		gsupc->link = NULL;
+	}
+	talloc_free(gsupc);
+}
+
+int gsup_client_send(struct gsup_client *gsupc, struct msgb *msg)
+{
+	if (!gsupc) {
+		msgb_free(msg);
+		return -ENOTCONN;
+	}
+
+	if (!gsupc->is_connected) {
+		msgb_free(msg);
+		return -EAGAIN;
+	}
+
+	client_send(gsupc, IPAC_PROTO_EXT_GSUP, msg);
+
+	return 0;
+}
+
+struct msgb *gsup_client_msgb_alloc(void)
+{
+	return msgb_alloc_headroom(4000, 64, __func__);
+}
diff --git a/openbsc/src/libcommon/gsup_test_client.c b/openbsc/src/libcommon/gsup_test_client.c
new file mode 100644
index 0000000..1889c6f
--- /dev/null
+++ b/openbsc/src/libcommon/gsup_test_client.c
@@ -0,0 +1,299 @@
+#include <string.h>
+#include <stdio.h>
+#include <errno.h>
+#include <signal.h>
+
+#include <osmocom/core/linuxlist.h>
+#include <osmocom/core/msgb.h>
+#include <osmocom/core/select.h>
+#include <osmocom/core/application.h>
+#include <osmocom/gsm/gsup.h>
+
+#include <openbsc/gsup_client.h>
+#include <openbsc/debug.h>
+
+static struct gsup_client *g_gc;
+
+
+/***********************************************************************
+ * IMSI Operation
+ ***********************************************************************/
+static LLIST_HEAD(g_imsi_ops);
+
+struct imsi_op_stats {
+	uint32_t num_alloc;
+	uint32_t num_released;
+	uint32_t num_rx_success;
+	uint32_t num_rx_error;
+	uint32_t num_timeout;
+};
+
+enum imsi_op_type {
+	IMSI_OP_SAI,
+	IMSI_OP_LU,
+	IMSI_OP_ISD,
+	_NUM_IMSI_OP
+};
+
+static const struct value_string imsi_op_names[] = {
+	{ IMSI_OP_SAI, "SAI" },
+	{ IMSI_OP_LU, "LU" },
+	{ IMSI_OP_ISD, "ISD" },
+	{ 0, NULL }
+};
+
+static struct imsi_op_stats imsi_op_stats[_NUM_IMSI_OP];
+
+struct imsi_op {
+	struct llist_head list;
+	char imsi[17];
+	enum imsi_op_type type;
+	struct osmo_timer_list timer;
+};
+
+static struct imsi_op *imsi_op_find(const char *imsi,
+			     enum imsi_op_type type)
+{
+	struct imsi_op *io;
+
+	llist_for_each_entry(io, &g_imsi_ops, list) {
+		if (!strcmp(io->imsi, imsi) && io->type == type)
+			return io;
+	}
+	return NULL;
+}
+
+static void imsi_op_timer_cb(void *data);
+
+static struct imsi_op *imsi_op_alloc(void *ctx, const char *imsi,
+				enum imsi_op_type type)
+{
+	struct imsi_op *io;
+
+	if (imsi_op_find(imsi, type))
+		return NULL;
+
+	io = talloc_zero(ctx, struct imsi_op);
+	strncpy(io->imsi, imsi, sizeof(io->imsi));
+	io->imsi[sizeof(io->imsi)-1] = '\0';
+	io->type = type;
+	io->timer.cb = imsi_op_timer_cb;
+	io->timer.data = io;
+	llist_add(&io->list, &g_imsi_ops);
+	imsi_op_stats[type].num_alloc++;
+
+	return io;
+}
+
+static void imsi_op_release(struct imsi_op *io)
+{
+	osmo_timer_del(&io->timer);
+	llist_del(&io->list);
+	imsi_op_stats[io->type].num_released++;
+	talloc_free(io);
+}
+
+static void imsi_op_timer_cb(void *data)
+{
+	struct imsi_op *io = data;
+	printf("%s: Timer expiration\n", io->imsi);
+	imsi_op_stats[io->type].num_timeout++;
+	imsi_op_release(io);
+}
+
+/* allocate + generate + send Send-Auth-Info */
+int req_auth_info(const char *imsi)
+{
+	struct imsi_op *io = imsi_op_alloc(g_gc, imsi, IMSI_OP_SAI);
+	struct osmo_gsup_message gsup = {0};
+	struct msgb *msg = msgb_alloc_headroom(1200, 200, __func__);
+
+	strncpy(gsup.imsi, io->imsi, sizeof(gsup.imsi));
+	gsup.message_type = OSMO_GSUP_MSGT_SEND_AUTH_INFO_REQUEST;
+
+	osmo_gsup_encode(msg, &gsup);
+
+	return gsup_client_send(g_gc, msg);
+}
+
+/* allocate + generate + send Send-Auth-Info */
+int req_loc_upd(const char *imsi)
+{
+	struct imsi_op *io = imsi_op_alloc(g_gc, imsi, IMSI_OP_LU);
+	struct osmo_gsup_message gsup = {0};
+	struct msgb *msg = msgb_alloc_headroom(1200, 200, __func__);
+
+	strncpy(gsup.imsi, io->imsi, sizeof(gsup.imsi));
+	gsup.message_type = OSMO_GSUP_MSGT_UPDATE_LOCATION_REQUEST;
+
+	osmo_gsup_encode(msg, &gsup);
+
+	return gsup_client_send(g_gc, msg);
+}
+
+int resp_isd(struct imsi_op *io)
+{
+	struct osmo_gsup_message gsup = {0};
+	struct msgb *msg = msgb_alloc_headroom(1200, 200, __func__);
+
+	strncpy(gsup.imsi, io->imsi, sizeof(gsup.imsi));
+	gsup.message_type = OSMO_GSUP_MSGT_INSERT_DATA_RESULT;
+
+	osmo_gsup_encode(msg, &gsup);
+
+	imsi_op_release(io);
+
+	return gsup_client_send(g_gc, msg);
+}
+
+/* receive an incoming GSUP message */
+static void imsi_op_rx_gsup(struct imsi_op *io, const struct osmo_gsup_message *gsup)
+{
+	int is_error = 0;
+
+	if (OSMO_GSUP_IS_MSGT_ERROR(gsup->message_type)) {
+		imsi_op_stats[io->type].num_rx_error++;
+		is_error = 1;
+	} else
+		imsi_op_stats[io->type].num_rx_success++;
+
+	switch (io->type) {
+	case IMSI_OP_SAI:
+		printf("%s; SAI Response%s\n", io->imsi, is_error ? ": ERROR" : "");
+		/* now that we have auth tuples, request LU */
+		req_loc_upd(io->imsi);
+		imsi_op_release(io);
+		break;
+	case IMSI_OP_LU:
+		printf("%s; LU Response%s\n", io->imsi, is_error ? ": ERROR" : "");
+		imsi_op_release(io);
+		break;
+	case IMSI_OP_ISD:
+		printf("%s; ISD Request%s\n", io->imsi, is_error ? ": ERROR" : "");
+		resp_isd(io);
+		break;
+	default:
+		printf("%s: Unknown\n", io->imsi);
+		imsi_op_release(io);
+		break;
+	}
+}
+
+static int op_type_by_gsup_msgt(enum osmo_gsup_message_type msg_type)
+{
+	switch (msg_type) {
+	case OSMO_GSUP_MSGT_SEND_AUTH_INFO_RESULT:
+	case OSMO_GSUP_MSGT_SEND_AUTH_INFO_ERROR:
+		return IMSI_OP_SAI;
+	case OSMO_GSUP_MSGT_UPDATE_LOCATION_RESULT:
+	case OSMO_GSUP_MSGT_UPDATE_LOCATION_ERROR:
+		return IMSI_OP_LU;
+	case OSMO_GSUP_MSGT_INSERT_DATA_REQUEST:
+		return IMSI_OP_ISD;
+	default:
+		printf("Unknown GSUP msg_type %u\n", msg_type);
+		return -1;
+	}
+}
+
+static int gsupc_read_cb(struct gsup_client *gsupc, struct msgb *msg)
+{
+	struct osmo_gsup_message gsup_msg = {0};
+	struct imsi_op *io;
+	int rc;
+
+	DEBUGP(DGPRS, "Rx GSUP %s\n", osmo_hexdump(msgb_l2(msg), msgb_l2len(msg)));
+
+	rc = osmo_gsup_decode(msgb_l2(msg), msgb_l2len(msg), &gsup_msg);
+	if (rc < 0)
+		return rc;
+
+	if (!gsup_msg.imsi[0])
+		return -1;
+
+	rc = op_type_by_gsup_msgt(gsup_msg.message_type);
+	if (rc < 0)
+		return rc;
+
+	switch (rc) {
+	case IMSI_OP_SAI:
+	case IMSI_OP_LU:
+		io = imsi_op_find(gsup_msg.imsi, rc);
+		if (!io)
+			return -1;
+		break;
+	case IMSI_OP_ISD:
+		/* ISD is an inbound transaction */
+		io = imsi_op_alloc(g_gc, gsup_msg.imsi, IMSI_OP_ISD);
+		break;
+	}
+
+	imsi_op_rx_gsup(io, &gsup_msg);
+	msgb_free(msg);
+
+	return 0;
+}
+
+static void print_report(void)
+{
+	unsigned int i;
+
+	for (i = 0; i < ARRAY_SIZE(imsi_op_stats); i++) {
+		struct imsi_op_stats *st = &imsi_op_stats[i];
+		const char *name = get_value_string(imsi_op_names, i);
+		printf("%s: %u alloc, %u released, %u success, %u error , %u tout\n",
+			name, st->num_alloc, st->num_released, st->num_rx_success,
+			st->num_rx_error, st->num_timeout);
+	}
+}
+
+static void sig_cb(int sig)
+{
+	switch (sig) {
+	case SIGINT:
+		print_report();
+		exit(0);
+		break;
+	}
+}
+
+void *tall_bsc_ctx = NULL;
+
+/* default categories */
+static struct log_info_cat default_categories[] = {
+};
+
+static const struct log_info gsup_test_client_log_info = {
+	.cat = default_categories,
+	.num_cat = ARRAY_SIZE(default_categories),
+};
+
+int main(int argc, char **argv)
+{
+	unsigned long long i;
+	char *server_host = "127.0.0.1";
+	uint16_t server_port = 2222;
+
+	osmo_init_logging(&gsup_test_client_log_info);
+
+	g_gc = gsup_client_create(server_host, server_port, gsupc_read_cb,
+				       NULL);
+
+
+	signal(SIGINT, sig_cb);
+
+	for (i = 0; i < 10000; i++) {
+		unsigned long long imsi = 901790000000000 + i;
+		char imsi_buf[17];
+		snprintf(imsi_buf, sizeof(imsi_buf), "%015llu", imsi);
+		req_auth_info(imsi_buf);
+		osmo_select_main(0);
+	}
+
+	while (1) {
+		osmo_select_main(0);
+	}
+
+	print_report();
+	exit(0);
+}