diff --git a/tests/Makefile.am b/tests/Makefile.am
index ecb2b6c..1bb26ce 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -4,7 +4,8 @@
                  smscb/smscb_test bits/bitrev_test a5/a5_test		\
                  conv/conv_test auth/milenage_test lapd/lapd_test	\
                  gsm0808/gsm0808_test gsm0408/gsm0408_test		\
-		 gb/bssgp_fc_test logging/logging_test fr/fr_test	\
+		 gb/bssgp_fc_test gb/gprs_ns_test                       \
+		 logging/logging_test fr/fr_test	                \
 		 loggingrb/loggingrb_test strrb/strrb_test              \
 		 vty/vty_test
 
@@ -51,6 +52,9 @@
 gb_bssgp_fc_test_SOURCES = gb/bssgp_fc_test.c
 gb_bssgp_fc_test_LDADD = $(top_builddir)/src/libosmocore.la $(top_builddir)/src/gb/libosmogb.la
 
+gb_gprs_ns_test_SOURCES = gb/gprs_ns_test.c
+gb_gprs_ns_test_LDADD = $(top_builddir)/src/libosmocore.la $(top_builddir)/src/gb/libosmogb.la $(LIBRARY_DL)
+
 logging_logging_test_SOURCES = logging/logging_test.c
 logging_logging_test_LDADD = $(top_builddir)/src/libosmocore.la
 
@@ -92,6 +96,7 @@
              lapd/lapd_test.ok gsm0408/gsm0408_test.ok			\
              gsm0808/gsm0808_test.ok gb/bssgp_fc_tests.err		\
              gb/bssgp_fc_tests.ok gb/bssgp_fc_tests.sh			\
+             gb/gprs_ns_test.ok						\
              msgfile/msgfile_test.ok msgfile/msgconfig.cfg		\
              logging/logging_test.ok logging/logging_test.err		\
              fr/fr_test.ok loggingrb/logging_test.ok			\
diff --git a/tests/gb/gprs_ns_test.c b/tests/gb/gprs_ns_test.c
new file mode 100644
index 0000000..d07cc3d
--- /dev/null
+++ b/tests/gb/gprs_ns_test.c
@@ -0,0 +1,247 @@
+/* test routines for NS connection handling
+ * (C) 2013 by sysmocom s.f.m.c. GmbH
+ * Author: Jacob Erlbeck <jerlbeck@sysmocom.de>
+ */
+
+#undef _GNU_SOURCE
+#define _GNU_SOURCE
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <string.h>
+#include <getopt.h>
+#include <dlfcn.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+
+#include <osmocom/core/msgb.h>
+#include <osmocom/core/application.h>
+#include <osmocom/core/utils.h>
+#include <osmocom/core/logging.h>
+#include <osmocom/core/talloc.h>
+#include <osmocom/gprs/gprs_msgb.h>
+#include <osmocom/gprs/gprs_ns.h>
+#include <osmocom/gprs/gprs_bssgp.h>
+
+
+/* GPRS Network Service, PDU type: NS_RESET,
+ * Cause: O&M intervention, NS VCI: 0x1122, NSEI 0x1122
+ */
+static const unsigned char gprs_ns_reset[12] = {
+	0x02, 0x00, 0x81, 0x01, 0x01, 0x82, 0x11, 0x22,
+	0x04, 0x82, 0x11, 0x22
+};
+
+/* GPRS Network Service, PDU type: NS_RESET,
+ * Cause: O&M intervention, NS VCI: 0x3344, NSEI 0x1122
+ */
+static const unsigned char gprs_ns_reset_vci2[12] = {
+	0x02, 0x00, 0x81, 0x01, 0x01, 0x82, 0x33, 0x44,
+	0x04, 0x82, 0x11, 0x22
+};
+
+/* GPRS Network Service, PDU type: NS_RESET,
+ * Cause: O&M intervention, NS VCI: 0x1122, NSEI 0x3344
+ */
+static const unsigned char gprs_ns_reset_nsei2[12] = {
+	0x02, 0x00, 0x81, 0x01, 0x01, 0x82, 0x11, 0x22,
+	0x04, 0x82, 0x33, 0x44
+};
+
+/* GPRS Network Service, PDU type: NS_ALIVE */
+static const unsigned char gprs_ns_alive[1] = {
+	0x0a
+};
+
+/* GPRS Network Service, PDU type: NS_STATUS,
+ * Cause: PDU not compatible with the protocol state
+ * PDU: NS_ALIVE
+ */
+static const unsigned char gprs_ns_status_invalid_alive[7] = {
+	0x08, 0x00, 0x81, 0x0a, 0x02, 0x81, 0x0a
+};
+
+/* GPRS Network Service, PDU type: NS_ALIVE_ACK */
+static const unsigned char gprs_ns_alive_ack[1] = {
+	0x0b
+};
+
+/* GPRS Network Service, PDU type: NS_UNBLOCK */
+static const unsigned char gprs_ns_unblock[1] = {
+	0x06
+};
+
+
+/* GPRS Network Service, PDU type: NS_STATUS,
+ * Cause: PDU not compatible with the protocol state
+ * PDU: NS_RESET_ACK, NS VCI: 0x1122, NSEI 0x1122
+ */
+static const unsigned char gprs_ns_status_invalid_reset_ack[15] = {
+	0x08, 0x00, 0x81, 0x0a, 0x02, 0x89, 0x03, 0x01,
+	0x82, 0x11, 0x22, 0x04, 0x82, 0x11, 0x22
+};
+
+/* GPRS Network Service, PDU type: NS_UNITDATA, BVCI 0 */
+static const unsigned char gprs_bssgp_reset[22] = {
+	0x00, 0x00, 0x00, 0x00, 0x22, 0x04, 0x82, 0x4a,
+	0x2e, 0x07, 0x81, 0x08, 0x08, 0x88, 0x10, 0x20,
+	0x30, 0x40, 0x50, 0x60, 0x10, 0x00
+};
+
+int gprs_ns_rcvmsg(struct gprs_ns_inst *nsi, struct msgb *msg,
+		   struct sockaddr_in *saddr, enum gprs_ns_ll ll);
+
+/* override */
+int gprs_ns_callback(enum gprs_ns_evt event, struct gprs_nsvc *nsvc,
+			 struct msgb *msg, uint16_t bvci)
+{
+	printf("CALLBACK, event %d, msg length %d, bvci 0x%04x\n%s\n\n",
+			event, msgb_bssgp_len(msg), bvci,
+			osmo_hexdump(msgb_bssgph(msg), msgb_bssgp_len(msg)));
+	return 0;
+}
+
+/* override */
+ssize_t sendto(int sockfd, const void *buf, size_t len, int flags,
+		const struct sockaddr *dest_addr, socklen_t addrlen)
+{
+	typedef ssize_t (*sendto_t)(int, const void *, size_t, int,
+			const struct sockaddr *, socklen_t);
+	static sendto_t real_sendto = NULL;
+
+	if (!real_sendto)
+		real_sendto = dlsym(RTLD_NEXT, "sendto");
+
+	if (sockfd != 0xdead && ((struct sockaddr_in *)dest_addr)->sin_addr.s_addr != htonl(0x01020304))
+		return real_sendto(sockfd, buf, len, flags, dest_addr, addrlen);
+
+	printf("RESPONSE, msg length %d\n%s\n\n", len, osmo_hexdump(buf, len));
+
+	return len;
+}
+
+static int gprs_process_message(struct gprs_ns_inst *nsi, const char *text, struct sockaddr_in *peer, const unsigned char* data, size_t data_len)
+{
+	struct msgb *msg;
+	int ret;
+	if (data_len > NS_ALLOC_SIZE - NS_ALLOC_HEADROOM) {
+		fprintf(stderr, "message too long: %d\n", data_len);
+		return -1;
+	}
+
+	msg = gprs_ns_msgb_alloc();
+	memmove(msg->data, data, data_len);
+	msg->l2h = msg->data;
+	msgb_put(msg, data_len);
+
+	printf("PROCESSING %s from 0x%08x:%d\n%s\n\n",
+	       text, ntohl(peer->sin_addr.s_addr), ntohs(peer->sin_port),
+	       osmo_hexdump(data, data_len));
+
+	ret = gprs_ns_rcvmsg(nsi, msg, peer, GPRS_NS_LL_UDP);
+
+	printf("result (%s) = %d\n\n", text, ret);
+
+	msgb_free(msg);
+
+	return ret;
+}
+
+static void gprs_dump_nsi(struct gprs_ns_inst *nsi)
+{
+	struct gprs_nsvc *nsvc;
+
+	printf("Current NS-VCIs:\n");
+	llist_for_each_entry(nsvc, &nsi->gprs_nsvcs, list) {
+		struct sockaddr_in *peer = &(nsvc->ip.bts_addr);
+		printf("    VCI 0x%04x, NSEI 0x%04x, peer 0x%08x:%d\n",
+		       nsvc->nsvci, nsvc->nsei,
+		       ntohl(peer->sin_addr.s_addr), ntohs(peer->sin_port)
+		      );
+	}
+	printf("\n");
+}
+
+static void test_ns()
+{
+	struct gprs_ns_inst *nsi = gprs_ns_instantiate(gprs_ns_callback, NULL);
+	struct sockaddr_in peer[4] = {{0},};
+
+	peer[0].sin_family = AF_INET;
+	peer[0].sin_port = htons(1111);
+	peer[0].sin_addr.s_addr = htonl(0x01020304);
+	peer[1].sin_family = AF_INET;
+	peer[1].sin_port = htons(2222);
+	peer[1].sin_addr.s_addr = htonl(0x01020304);
+	peer[2].sin_family = AF_INET;
+	peer[2].sin_port = htons(3333);
+	peer[2].sin_addr.s_addr = htonl(0x01020304);
+	peer[3].sin_family = AF_INET;
+	peer[3].sin_port = htons(4444);
+	peer[3].sin_addr.s_addr = htonl(0x01020304);
+
+	gprs_process_message(nsi, "RESET", &peer[0],
+			     gprs_ns_reset, sizeof(gprs_ns_reset));
+	gprs_dump_nsi(nsi);
+	gprs_process_message(nsi, "ALIVE", &peer[0],
+			     gprs_ns_alive, sizeof(gprs_ns_alive));
+	gprs_process_message(nsi, "UNBLOCK", &peer[0],
+			     gprs_ns_unblock, sizeof(gprs_ns_unblock));
+	gprs_process_message(nsi, "BSSGP RESET", &peer[0],
+			     gprs_bssgp_reset, sizeof(gprs_bssgp_reset));
+
+	printf("--- Peer port changes, RESET, message remains unchanged ---\n\n");
+
+	gprs_process_message(nsi, "RESET", &peer[1],
+			     gprs_ns_reset, sizeof(gprs_ns_reset));
+	gprs_dump_nsi(nsi);
+
+	printf("--- Peer port changes, RESET, VCI changes ---\n\n");
+
+	gprs_process_message(nsi, "RESET", &peer[2],
+			     gprs_ns_reset_vci2, sizeof(gprs_ns_reset_vci2));
+	gprs_dump_nsi(nsi);
+
+	printf("--- Peer port changes, RESET, NSEI changes ---\n\n");
+
+	gprs_process_message(nsi, "RESET", &peer[3],
+			     gprs_ns_reset_nsei2, sizeof(gprs_ns_reset_nsei2));
+	gprs_dump_nsi(nsi);
+
+	printf("--- Peer port 3333, RESET, VCI is changed back ---\n\n");
+
+	gprs_process_message(nsi, "RESET", &peer[2],
+			     gprs_ns_reset, sizeof(gprs_ns_reset));
+	gprs_dump_nsi(nsi);
+
+	printf("--- Peer port 4444, RESET, NSEI is changed back ---\n\n");
+
+	gprs_process_message(nsi, "RESET", &peer[3],
+			     gprs_ns_reset, sizeof(gprs_ns_reset));
+	gprs_dump_nsi(nsi);
+
+	gprs_ns_destroy(nsi);
+	nsi = NULL;
+}
+
+
+int bssgp_prim_cb(struct osmo_prim_hdr *oph, void *ctx)
+{
+	return -1;
+}
+
+static struct log_info info = {};
+
+int main(int argc, char **argv)
+{
+	osmo_init_logging(&info);
+	log_set_use_color(osmo_stderr_target, 0);
+	log_set_print_filename(osmo_stderr_target, 0);
+
+	printf("===== NS protocol test START\n");
+	test_ns();
+	printf("===== NS protocol test END\n\n");
+
+	exit(EXIT_SUCCESS);
+}
diff --git a/tests/gb/gprs_ns_test.ok b/tests/gb/gprs_ns_test.ok
new file mode 100644
index 0000000..4a44907
--- /dev/null
+++ b/tests/gb/gprs_ns_test.ok
@@ -0,0 +1,124 @@
+===== NS protocol test START
+PROCESSING RESET from 0x01020304:1111
+02 00 81 01 01 82 11 22 04 82 11 22 
+
+RESPONSE, msg length 1
+0a 
+
+RESPONSE, msg length 9
+03 01 82 11 22 04 82 11 22 
+
+result (RESET) = 9
+
+Current NS-VCIs:
+    VCI 0x1122, NSEI 0x1122, peer 0x01020304:1111
+
+PROCESSING ALIVE from 0x01020304:1111
+0a 
+
+RESPONSE, msg length 1
+0b 
+
+result (ALIVE) = 1
+
+PROCESSING UNBLOCK from 0x01020304:1111
+06 
+
+RESPONSE, msg length 1
+07 
+
+result (UNBLOCK) = 1
+
+PROCESSING BSSGP RESET from 0x01020304:1111
+00 00 00 00 22 04 82 4a 2e 07 81 08 08 88 10 20 30 40 50 60 10 00 
+
+CALLBACK, event 0, msg length 18, bvci 0x0000
+22 04 82 4a 2e 07 81 08 08 88 10 20 30 40 50 60 10 00 
+
+result (BSSGP RESET) = 0
+
+--- Peer port changes, RESET, message remains unchanged ---
+
+PROCESSING RESET from 0x01020304:2222
+02 00 81 01 01 82 11 22 04 82 11 22 
+
+RESPONSE, msg length 1
+0a 
+
+RESPONSE, msg length 9
+03 01 82 11 22 04 82 11 22 
+
+result (RESET) = 9
+
+Current NS-VCIs:
+    VCI 0x1122, NSEI 0x1122, peer 0x01020304:2222
+
+--- Peer port changes, RESET, VCI changes ---
+
+PROCESSING RESET from 0x01020304:3333
+02 00 81 01 01 82 33 44 04 82 11 22 
+
+RESPONSE, msg length 1
+0a 
+
+RESPONSE, msg length 9
+03 01 82 33 44 04 82 11 22 
+
+result (RESET) = 9
+
+Current NS-VCIs:
+    VCI 0x3344, NSEI 0x1122, peer 0x01020304:3333
+
+--- Peer port changes, RESET, NSEI changes ---
+
+PROCESSING RESET from 0x01020304:4444
+02 00 81 01 01 82 11 22 04 82 33 44 
+
+RESPONSE, msg length 1
+0a 
+
+RESPONSE, msg length 9
+03 01 82 11 22 04 82 33 44 
+
+result (RESET) = 9
+
+Current NS-VCIs:
+    VCI 0x1122, NSEI 0x3344, peer 0x01020304:4444
+    VCI 0x3344, NSEI 0x1122, peer 0x01020304:3333
+
+--- Peer port 3333, RESET, VCI is changed back ---
+
+PROCESSING RESET from 0x01020304:3333
+02 00 81 01 01 82 11 22 04 82 11 22 
+
+RESPONSE, msg length 1
+0a 
+
+RESPONSE, msg length 9
+03 01 82 11 22 04 82 11 22 
+
+result (RESET) = 9
+
+Current NS-VCIs:
+    VCI 0x1122, NSEI 0x3344, peer 0x01020304:4444
+    VCI 0x1122, NSEI 0x1122, peer 0x01020304:3333
+
+--- Peer port 4444, RESET, NSEI is changed back ---
+
+PROCESSING RESET from 0x01020304:4444
+02 00 81 01 01 82 11 22 04 82 11 22 
+
+RESPONSE, msg length 1
+0a 
+
+RESPONSE, msg length 9
+03 01 82 11 22 04 82 11 22 
+
+result (RESET) = 9
+
+Current NS-VCIs:
+    VCI 0x1122, NSEI 0x1122, peer 0x01020304:4444
+    VCI 0x1122, NSEI 0x1122, peer 0x01020304:3333
+
+===== NS protocol test END
+
diff --git a/tests/testsuite.at b/tests/testsuite.at
index 97d0adc..0685832 100644
--- a/tests/testsuite.at
+++ b/tests/testsuite.at
@@ -106,6 +106,12 @@
 AT_CHECK([$abs_top_builddir/tests/vty/vty_test], [0], [expout], [ignore])
 AT_CLEANUP
 
+AT_SETUP([gprs-ns])
+AT_KEYWORDS([gprs-ns])
+cat $abs_srcdir/gb/gprs_ns_test.ok > expout
+AT_CHECK([$abs_top_builddir/tests/gb/gprs_ns_test], [0], [expout], [ignore])
+AT_CLEANUP
+
 AT_SETUP([bssgp-fc])
 AT_KEYWORDS([bssgp-fc])
 cat $abs_srcdir/gb/bssgp_fc_tests.ok > expout