diff --git a/openbsc/src/gprs/gsup_test_client.c b/openbsc/src/gprs/gsup_test_client.c
new file mode 100644
index 0000000..5f123b8
--- /dev/null
+++ b/openbsc/src/gprs/gsup_test_client.c
@@ -0,0 +1,304 @@
+#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/gprs_gsup_client.h>
+#include <openbsc/debug.h>
+
+static struct gprs_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 gprs_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 gprs_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 gprs_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 gprs_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 gprs_categories[] = {
+	[DGPRS] = {
+		.name = "DGPRS",
+		.description = "GPRS Packet Service",
+		.enabled = 1, .loglevel = LOGL_INFO,
+	},
+};
+
+static const struct log_info gprs_log_info = {
+	.cat = gprs_categories,
+	.num_cat = ARRAY_SIZE(gprs_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(&gprs_log_info);
+
+	g_gc = gprs_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);
+}