diff --git a/openbsc/include/openbsc/gtphub.h b/openbsc/include/openbsc/gtphub.h
index 5298505..05eee85 100644
--- a/openbsc/include/openbsc/gtphub.h
+++ b/openbsc/include/openbsc/gtphub.h
@@ -27,6 +27,8 @@
 #include <osmocom/core/select.h>
 #include <osmocom/core/timer.h>
 
+#include <openbsc/gprs_sgsn.h>
+
 
 /* support */
 
@@ -363,6 +365,18 @@
 	struct llist_head peers;
 };
 
+struct gtphub_resolved_ggsn {
+	struct llist_head entry;
+	struct expiring_item expiry_entry;
+
+	/* The APN OI, the Operator Identifier, is the combined address,
+	 * including parts of the IMSI and APN NI, and ending with ".gprs". */
+	char apn_oi_str[GSM_APN_LENGTH];
+
+	/* Which address and port we resolved that to. */
+	struct gtphub_peer_port *peer;
+};
+
 struct gtphub {
 	struct gtphub_bind to_sgsns[GTPH_PLANE_N];
 	struct gtphub_bind to_ggsns[GTPH_PLANE_N];
@@ -376,6 +390,9 @@
 	struct nr_map tei_map[GTPH_PLANE_N];
 	struct nr_pool tei_pool[GTPH_PLANE_N];
 
+	struct llist_head ggsn_lookups; /* opaque (gtphub_ext.c) */
+	struct llist_head resolved_ggsns; /* struct gtphub_resolved_ggsn */
+
 	struct osmo_timer_list gc_timer;
 	struct expiry expire_seq_maps;
 	struct expiry expire_tei_maps;
@@ -420,5 +437,16 @@
 				 struct osmo_fd **to_ofd,
 				 struct osmo_sockaddr *to_addr);
 
+struct gtphub_peer_port *gtphub_port_have(struct gtphub *hub,
+					  struct gtphub_bind *bind,
+					  const struct gsn_addr *addr,
+					  uint16_t port);
+
 struct gtphub_peer_port *gtphub_port_find_sa(const struct gtphub_bind *bind,
 					     const struct osmo_sockaddr *addr);
+
+void gtphub_resolved_ggsn(struct gtphub *hub, const char *apn_oi_str,
+			  struct gsn_addr *resolved_addr,
+			  time_t now);
+
+const char *gtphub_port_str(struct gtphub_peer_port *port);
diff --git a/openbsc/src/gprs/Makefile.am b/openbsc/src/gprs/Makefile.am
index 0dd38f9..5212c67 100644
--- a/openbsc/src/gprs/Makefile.am
+++ b/openbsc/src/gprs/Makefile.am
@@ -35,7 +35,9 @@
 			-lgtp $(OSMO_LIBS) $(LIBOSMOABIS_LIBS) $(LIBCARES_LIBS) \
 			$(LIBCRYPTO_LIBS) -lrt
 
-osmo_gtphub_SOURCES =	gtphub_main.c gtphub.c gtphub_ext.c gtphub_vty.c
+osmo_gtphub_SOURCES =	gtphub_main.c gtphub.c gtphub_ext.c gtphub_vty.c \
+			sgsn_ares.c gprs_utils.c
 osmo_gtphub_LDADD = 	\
 			$(top_builddir)/src/libcommon/libcommon.a \
-			-lgtp $(LIBOSMOCORE_LIBS) $(LIBOSMOVTY_LIBS) -lrt
+			-lgtp $(LIBOSMOCORE_LIBS) $(LIBOSMOGSM_LIBS) $(LIBOSMOVTY_LIBS) \
+			$(LIBCARES_LIBS) -lrt
diff --git a/openbsc/src/gprs/gprs_utils.c b/openbsc/src/gprs/gprs_utils.c
index 2293f02..ad479db 100644
--- a/openbsc/src/gprs/gprs_utils.c
+++ b/openbsc/src/gprs/gprs_utils.c
@@ -114,7 +114,9 @@
 }
 
 /* TODO: Move these conversion functions to a utils file. */
-/**
+/* TODO: consolidate with gprs_apn2str(). */
+/** memmove apn_enc to out_str, replacing the length octets in apn_enc with '.'
+ * (omitting the first one) and terminating with a '\0'.
  * out_str needs to have rest_chars amount of bytes or 1 whatever is bigger.
  */
 char * gprs_apn_to_str(char *out_str, const uint8_t *apn_enc, size_t rest_chars)
diff --git a/openbsc/src/gprs/gtphub.c b/openbsc/src/gprs/gtphub.c
index 440f00f..eae4cf2 100644
--- a/openbsc/src/gprs/gtphub.c
+++ b/openbsc/src/gprs/gtphub.c
@@ -33,11 +33,13 @@
 
 #include <openbsc/gtphub.h>
 #include <openbsc/debug.h>
+#include <openbsc/gprs_utils.h>
 
 #include <osmocom/core/utils.h>
 #include <osmocom/core/logging.h>
 #include <osmocom/core/socket.h>
 
+
 #define GTPHUB_DEBUG 1
 
 static const int GTPH_GC_TICK_SECONDS = 1;
@@ -345,13 +347,13 @@
  * The first IEI is reached by passing i = 0.
  * imsi must point at allocated space of (at least) 8 bytes.
  * Return 1 on success, or 0 if not found. */
-static int get_ie_imsi(union gtpie_member *ie[], uint8_t *imsi, int i)
+static int get_ie_imsi(union gtpie_member *ie[], int i, uint8_t *imsi)
 {
 	return gtpie_gettv0(ie, GTPIE_IMSI, i, imsi, 8) == 0;
 }
 
 /* Analogous to get_ie_imsi(). nsapi must point at a single uint8_t. */
-static int get_ie_nsapi(union gtpie_member *ie[], uint8_t *nsapi, int i)
+static int get_ie_nsapi(union gtpie_member *ie[], int i, uint8_t *nsapi)
 {
 	return gtpie_gettv1(ie, GTPIE_NSAPI, i, nsapi) == 0;
 }
@@ -379,6 +381,33 @@
 	return str;
 }
 
+static const char *get_ie_imsi_str(union gtpie_member *ie[], int i)
+{
+	uint8_t imsi_buf[8];
+	if (!get_ie_imsi(ie, i, imsi_buf))
+		return NULL;
+	return imsi_to_str(imsi_buf);
+}
+
+static const char *get_ie_apn_str(union gtpie_member *ie[])
+{
+	static char apn_buf[GSM_APN_LENGTH];
+	unsigned int len;
+	if (gtpie_gettlv(ie, GTPIE_APN, 0,
+			 &len, apn_buf, sizeof(apn_buf)) != 0)
+		return NULL;
+
+	if (!len)
+		return NULL;
+
+	if (len > (sizeof(apn_buf) - 1))
+		len = sizeof(apn_buf) - 1;
+	apn_buf[len] = '\0';
+
+	return  gprs_apn_to_str(apn_buf, (uint8_t*)apn_buf, len);
+}
+
+
 /* Validate header, and index information elements. Write decoded packet
  * information to *res. res->data will point at the given data buffer. On
  * error, p->rc is set <= 0 (see enum gtp_rc). */
@@ -416,15 +445,15 @@
 	int i;
 
 	for (i = 0; i < 10; i++) {
-		uint8_t imsi[8];
-		if (!get_ie_imsi(res->ie, imsi, i))
+		const char *imsi = get_ie_imsi_str(res->ie, i);
+		if (!imsi)
 			break;
-		LOG("| IMSI %s\n", imsi_to_str(imsi));
+		LOG("| IMSI %s\n", imsi);
 	}
 
 	for (i = 0; i < 10; i++) {
 		uint8_t nsapi;
-		if (!get_ie_nsapi(res->ie, &nsapi, i))
+		if (!get_ie_nsapi(res->ie, i, &nsapi))
 			break;
 		LOG("| NSAPI %d\n", (int)nsapi);
 	}
@@ -481,7 +510,6 @@
 			expiring_item_del(m);
 			expired ++;
 		} else {
-			LOG("Not expired: %d > %d\n", (int)m->expiry, (int)now);
 			/* The items are added sorted by expiry. So when we hit
 			 * an unexpired entry, only more unexpired ones will
 			 * follow. */
@@ -654,19 +682,15 @@
 						    struct gtp_packet_desc *p);
 
 /* See gtphub_ext.c (wrapped by unit test) */
-int gtphub_resolve_ggsn_addr(struct gtphub *hub,
-			     struct osmo_sockaddr *result,
-			     struct gtp_packet_desc *p);
+struct gtphub_peer_port *gtphub_resolve_ggsn_addr(struct gtphub *hub,
+						  const char *imsi_str,
+						  const char *apn_ni_str);
+int gtphub_ares_init(struct gtphub *hub);
 
 static struct gtphub_peer_port *gtphub_port_find(const struct gtphub_bind *bind,
 						 const struct gsn_addr *addr,
 						 uint16_t port);
 
-static struct gtphub_peer_port *gtphub_port_have(struct gtphub *hub,
-						 struct gtphub_bind *bind,
-						 const struct gsn_addr *addr,
-						 uint16_t port);
-
 static void gtphub_zero(struct gtphub *hub)
 {
 	ZERO_STRUCT(hub);
@@ -833,7 +857,7 @@
 	return gtphub_peer_strb(peer, buf, sizeof(buf));
 }
 
-static const char *gtphub_port_str(struct gtphub_peer_port *port)
+const char *gtphub_port_str(struct gtphub_peer_port *port)
 {
 	static char buf[256];
 	return gtphub_port_strb(port, buf, sizeof(buf));
@@ -1562,6 +1586,49 @@
 	return received;
 }
 
+static void resolved_gssn_del_cb(struct expiring_item *expi)
+{
+	struct gtphub_resolved_ggsn *ggsn;
+	ggsn = container_of(expi, struct gtphub_resolved_ggsn, expiry_entry);
+
+	gtphub_port_ref_count_dec(ggsn->peer);
+	llist_del(&ggsn->entry);
+
+	ggsn->expiry_entry.del_cb = 0;
+	expiring_item_del(&ggsn->expiry_entry);
+
+	talloc_free(ggsn);
+}
+
+void gtphub_resolved_ggsn(struct gtphub *hub, const char *apn_oi_str,
+			  struct gsn_addr *resolved_addr,
+			  time_t now)
+{
+	struct gtphub_peer_port *pp;
+	struct gtphub_resolved_ggsn *ggsn;
+
+	pp = gtphub_port_have(hub, &hub->to_ggsns[GTPH_PLANE_CTRL],
+			      resolved_addr, 2123);
+	if (!pp) {
+		LOGERR("Internal: Cannot create/find peer '%s'\n",
+		       gsn_addr_to_str(resolved_addr));
+		return;
+	}
+
+	ggsn = talloc_zero(osmo_gtphub_ctx, struct gtphub_resolved_ggsn);
+	OSMO_ASSERT(ggsn);
+
+	ggsn->peer = pp;
+	gtphub_port_ref_count_inc(pp);
+
+	strncpy(ggsn->apn_oi_str, apn_oi_str, sizeof(ggsn->apn_oi_str));
+
+	ggsn->expiry_entry.del_cb = resolved_gssn_del_cb;
+	expiry_add(&hub->expire_tei_maps, &ggsn->expiry_entry, now);
+
+	llist_add(&ggsn->entry, &hub->resolved_ggsns);
+}
+
 static int gtphub_gc_peer_port(struct gtphub_peer_port *pp)
 {
 	return pp->ref_count == 0;
@@ -1654,6 +1721,8 @@
 {
 	gtphub_zero(hub);
 
+	INIT_LLIST_HEAD(&hub->resolved_ggsns);
+
 	expiry_init(&hub->expire_seq_maps, GTPH_SEQ_MAPPING_EXPIRY_SECS);
 	expiry_init(&hub->expire_tei_maps, GTPH_TEI_MAPPING_EXPIRY_MINUTES * 60);
 
@@ -1693,6 +1762,7 @@
 	int rc;
 
 	gtphub_init(hub);
+	gtphub_ares_init(hub);
 
 	int plane_idx;
 	for (plane_idx = 0; plane_idx < GTPH_PLANE_N; plane_idx++) {
@@ -1882,10 +1952,10 @@
 	return pp;
 }
 
-static struct gtphub_peer_port *gtphub_port_have(struct gtphub *hub,
-						 struct gtphub_bind *bind,
-						 const struct gsn_addr *addr,
-						 uint16_t port)
+struct gtphub_peer_port *gtphub_port_have(struct gtphub *hub,
+					  struct gtphub_bind *bind,
+					  const struct gsn_addr *addr,
+					  uint16_t port)
 {
 	struct gtphub_peer_addr *a = gtphub_addr_have(hub, bind, addr);
 
@@ -1896,47 +1966,12 @@
 	return gtphub_addr_add_port(a, port);
 }
 
-/* port_override: <=0: use port from addr; >0: use this number as port. Return
- * NULL if the address cannot be parsed. */
-static struct gtphub_peer_port *gtphub_port_have_sockaddr(struct gtphub *hub,
-							  struct gtphub_bind *bind,
-							  const struct osmo_sockaddr *addr,
-							  int port_override)
-{
-	struct gsn_addr gsna;
-	uint16_t port;
-	if (gsn_addr_from_sockaddr(&gsna, &port, addr) != 0)
-		return NULL;
-
-	if (port_override > 0)
-		port = port_override;
-	return gtphub_port_have(hub, bind, &gsna, port);
-}
-
-static struct gtphub_peer_port *gtphub_have_ggsn(struct gtphub *hub,
-						 struct osmo_sockaddr *addr,
-						 unsigned int plane_idx,
-						 int port_override)
-{
-	if (port_override == 0)
-		port_override = gtphub_plane_idx_default_port[plane_idx];
-
-	return gtphub_port_have_sockaddr(hub, &hub->to_ggsns[plane_idx], addr,
-					 port_override);
-}
-
 static struct gtphub_peer_port *gtphub_resolve_ggsn(struct gtphub *hub,
 						    struct gtp_packet_desc *p)
 {
-	int rc;
-
-	struct osmo_sockaddr addr;
-
-	rc = gtphub_resolve_ggsn_addr(hub, &addr, p);
-	if (rc < 0)
-		return NULL;
-
-	return gtphub_have_ggsn(hub, &addr, p->plane_idx, -1);
+	return gtphub_resolve_ggsn_addr(hub,
+					get_ie_imsi_str(p->ie, 0),
+					get_ie_apn_str(p->ie));
 }
 
 
diff --git a/openbsc/src/gprs/gtphub_ext.c b/openbsc/src/gprs/gtphub_ext.c
index 0a4164c..d739614 100644
--- a/openbsc/src/gprs/gtphub_ext.c
+++ b/openbsc/src/gprs/gtphub_ext.c
@@ -24,35 +24,161 @@
  */
 
 #include <string.h>
+#include <unistd.h>
 
 #include <openbsc/gtphub.h>
+#include <openbsc/debug.h>
+
 #include <osmocom/core/utils.h>
+#include <osmocom/gsm/apn.h>
 
-#define __llist_first(head) (((head)->next == (head)) ? NULL : (head)->next)
-#define llist_first(head, type, entry) llist_entry(__llist_first(head), type, entry)
+/* TODO split GRX ares from sgsn into a separate struct and allow use without
+ * globals. */
+#include <openbsc/sgsn.h>
+extern struct sgsn_instance *sgsn;
 
-int gtphub_resolve_ggsn_addr(struct gtphub *hub,
-			     struct osmo_sockaddr *result,
-			     struct gtp_packet_desc *p)
+struct sgsn_instance sgsn_inst = { 0 };
+struct sgsn_instance *sgsn = &sgsn_inst;
+
+extern void *osmo_gtphub_ctx;
+
+int gtphub_ares_init(struct gtphub *hub)
 {
-	/* TODO  This is just hardcodedly returning the first known address.
-	 * Should resolve from actual subscriber data. */
-	struct gtphub_peer *peer = llist_first(&hub->to_ggsns[GTPH_PLANE_CTRL].peers,
-					       struct gtphub_peer, entry);
-	if (!peer)
-		return -1;
-
-	struct gtphub_peer_addr *pa = llist_first(&peer->addresses,
-						  struct gtphub_peer_addr, entry);
-	if (!pa)
-		return -1;
-
-	struct gtphub_peer_port *pp = llist_first(&pa->ports,
-						  struct gtphub_peer_port, entry);
-	if (!pp)
-		return -1;
-
-	*result = pp->sa;
-	return 0;
+	return sgsn_ares_init(sgsn);
 }
 
+struct ggsn_lookup {
+	struct llist_head entry;
+	struct expiring_item expiry_entry;
+
+	struct gtphub *hub;
+
+	char imsi_str[GSM_IMSI_LENGTH];
+	char apn_ni_str[GSM_APN_LENGTH];
+	char apn_oi_str[GSM_APN_LENGTH];
+	int have_3dig_mnc;
+};
+
+static int start_ares_query(struct ggsn_lookup *lookup);
+
+static void ggsn_lookup_cb(void *arg, int status, int timeouts, struct hostent *hostent)
+{
+	struct ggsn_lookup *lookup = arg;
+
+	if (status != ARES_SUCCESS) {
+		LOGP(DGTPHUB, LOGL_ERROR, "DNS query failed.\n");
+
+		/* Need to try with three digits now */
+		if (!lookup->have_3dig_mnc) {
+			lookup->have_3dig_mnc = 1;
+			if (start_ares_query(lookup) == 0)
+				return;
+		}
+
+		LOGP(DGTPHUB, LOGL_ERROR, "Failed to resolve GGSN.\n");
+		goto remove_from_queue;
+	}
+
+	struct gsn_addr resolved_addr;
+	if (hostent->h_length > sizeof(resolved_addr.buf)) {
+		LOGP(DGTPHUB, LOGL_ERROR, "Addr size too large: %d > %d\n",
+		     (int)hostent->h_length, (int)sizeof(resolved_addr.buf));
+		goto remove_from_queue;
+	}
+
+	/* Get the first addr from the list */
+	char *addr0 = hostent->h_addr_list[0];
+	if (!addr0) {
+		LOGP(DGTPHUB, LOGL_ERROR, "No host address.\n");
+		goto remove_from_queue;
+	}
+
+	memcpy(&resolved_addr.buf, addr0, hostent->h_length);
+	resolved_addr.len = hostent->h_length;
+
+	gtphub_resolved_ggsn(lookup->hub, lookup->apn_oi_str, &resolved_addr,
+			     gtphub_now());
+
+remove_from_queue:
+	expiring_item_del(&lookup->expiry_entry);
+}
+
+static void make_addr_str(struct ggsn_lookup *lookup)
+{
+	char *apn_oi_str;
+	apn_oi_str = osmo_apn_qualify_from_imsi(lookup->imsi_str,
+						lookup->apn_ni_str,
+						lookup->have_3dig_mnc);
+	strncpy(lookup->apn_oi_str, apn_oi_str, sizeof(lookup->apn_oi_str));
+	lookup->apn_oi_str[sizeof(lookup->apn_oi_str)-1] = '\0';
+}
+
+static int start_ares_query(struct ggsn_lookup *lookup)
+{
+	LOGP(DGTPHUB, LOGL_DEBUG, "Going to query %s\n", lookup->apn_oi_str);
+
+	int rc = sgsn_ares_query(sgsn, lookup->apn_oi_str, ggsn_lookup_cb, &lookup);
+	if (rc != 0)
+		LOGP(DGTPHUB, LOGL_ERROR, "Failed to start ares query.\n");
+	return rc;
+}
+
+static void ggsn_lookup_del_cb(struct expiring_item *expi)
+{
+	struct ggsn_lookup *ggsn;
+	ggsn = container_of(expi, struct ggsn_lookup, expiry_entry);
+
+	ggsn->expiry_entry.del_cb = 0;
+	expiring_item_del(expi);
+
+	llist_del(&ggsn->entry);
+	talloc_free(ggsn);
+}
+
+struct gtphub_peer_port *gtphub_resolve_ggsn_addr(struct gtphub *hub,
+						  const char *imsi_str,
+						  const char *apn_ni_str)
+{
+	struct ggsn_lookup *lookup = talloc_zero(osmo_gtphub_ctx, struct ggsn_lookup);
+
+	lookup->hub = hub;
+
+	strncpy(lookup->imsi_str, imsi_str, sizeof(lookup->imsi_str));
+	lookup->imsi_str[sizeof(lookup->imsi_str)-1] = '\0';
+
+	strncpy(lookup->apn_ni_str, apn_ni_str, sizeof(lookup->apn_ni_str));
+	lookup->apn_ni_str[sizeof(lookup->apn_ni_str)-1] = '\0';
+
+	make_addr_str(lookup);
+
+	struct ggsn_lookup *active;
+	llist_for_each_entry(active, &hub->ggsn_lookups, entry) {
+		if (strncmp(active->apn_oi_str, lookup->apn_oi_str,
+			    sizeof(lookup->apn_oi_str)) == 0) {
+			/* A query already pending. Just tip our hat. */
+			return NULL;
+		}
+	}
+
+	struct gtphub_resolved_ggsn *resolved;
+	llist_for_each_entry(resolved, &hub->resolved_ggsns, entry) {
+		if (strncmp(resolved->apn_oi_str, lookup->apn_oi_str,
+			    sizeof(lookup->apn_oi_str)) == 0) {
+			/* Already resolved. */
+			return resolved->peer;
+		}
+	}
+
+	/* Kick off a resolution, but so far return nothing. The hope is that
+	 * the peer will resend the request (a couple of times), and by then
+	 * the GGSN will be resolved. */
+
+	llist_add(&lookup->entry, &hub->ggsn_lookups);
+
+	lookup->expiry_entry.del_cb = ggsn_lookup_del_cb;
+	expiry_add(&hub->expire_seq_maps, &lookup->expiry_entry, gtphub_now());
+
+	start_ares_query(lookup);
+
+	return NULL;
+}
diff --git a/openbsc/src/gprs/sgsn_vty.c b/openbsc/src/gprs/sgsn_vty.c
index 3a73c9f..3f61163 100644
--- a/openbsc/src/gprs/sgsn_vty.c
+++ b/openbsc/src/gprs/sgsn_vty.c
@@ -110,6 +110,11 @@
 
 
 #define GSM48_MAX_APN_LEN	102	/* 10.5.6.1 */
+/* TODO: consolidate with gprs_apn_to_str(). */
+/** Copy apn to a static buffer, replacing the length octets in apn_enc with '.'
+ * and terminating with a '\0'. Return the static buffer.
+ * len: the length of the encoded APN (which has no terminating zero).
+ */
 static char *gprs_apn2str(uint8_t *apn, unsigned int len)
 {
 	static char apnbuf[GSM48_MAX_APN_LEN+1];
diff --git a/openbsc/tests/gtphub/Makefile.am b/openbsc/tests/gtphub/Makefile.am
index ecc6d62..d818811 100644
--- a/openbsc/tests/gtphub/Makefile.am
+++ b/openbsc/tests/gtphub/Makefile.am
@@ -11,10 +11,12 @@
 
 gtphub_test_SOURCES = gtphub_test.c
 gtphub_test_LDFLAGS = \
-	-Wl,--wrap=gtphub_resolve_ggsn_addr
+	-Wl,--wrap=gtphub_resolve_ggsn_addr \
+	-Wl,--wrap=gtphub_ares_init
 
 gtphub_test_LDADD = \
 	$(top_builddir)/src/gprs/gtphub.o \
+	$(top_builddir)/src/gprs/gprs_utils.o \
 	$(LIBOSMOCORE_LIBS) \
 	-lgtp -lrt
 
diff --git a/openbsc/tests/gtphub/gtphub_test.c b/openbsc/tests/gtphub/gtphub_test.c
index af8f3ed..81875f1 100644
--- a/openbsc/tests/gtphub/gtphub_test.c
+++ b/openbsc/tests/gtphub/gtphub_test.c
@@ -37,8 +37,6 @@
 
 #define EXPIRE_ALL ((60 * GTPH_TEI_MAPPING_EXPIRY_MINUTES) + 1)
 
-/* Make non-public API accessible */
-
 void gtphub_init(struct gtphub *hub);
 
 void *osmo_gtphub_ctx;
@@ -328,19 +326,75 @@
 
 
 /* override, requires '-Wl,--wrap=gtphub_resolve_ggsn_addr' */
-int __real_gtphub_resolve_ggsn_addr(struct gtphub *hub,
-				    struct osmo_sockaddr *result,
-				    struct gtp_packet_desc *p);
+struct gtphub_peer_port *__real_gtphub_resolve_ggsn_addr(struct gtphub *hub,
+							 const char *imsi_str,
+							 const char *apn_ni_str);
 
-struct osmo_sockaddr resolved_ggsn_addr = {.l = 0};
-int __wrap_gtphub_resolve_ggsn_addr(struct gtphub *hub,
-				    struct osmo_sockaddr *result,
-				    struct gtp_packet_desc *p)
+struct gsn_addr resolved_ggsn_addr = { 0 };
+uint16_t resolved_ggsn_port = 2123;
+char resolve_ggsn_got_imsi[256];
+char resolve_ggsn_got_ni[256];
+struct gtphub_peer_port *__wrap_gtphub_resolve_ggsn_addr(struct gtphub *hub,
+							 const char *imsi_str,
+							 const char *apn_ni_str)
 {
-	osmo_sockaddr_copy(result, &resolved_ggsn_addr);
-	printf("Wrap: returning GGSN addr: %s\n",
-	       osmo_sockaddr_to_str(result));
-	return (resolved_ggsn_addr.l != 0)? 0 : -1;
+	struct gtphub_peer_port *pp;
+	pp = gtphub_port_have(hub, &hub->to_ggsns[GTPH_PLANE_CTRL],
+			      &resolved_ggsn_addr, resolved_ggsn_port);
+	printf("Wrap: returning GGSN addr from imsi %s ni %s: %s\n",
+	       imsi_str, apn_ni_str, gtphub_port_str(pp));
+
+	if (imsi_str) {
+		strncpy(resolve_ggsn_got_imsi, imsi_str, sizeof(resolve_ggsn_got_imsi));
+		resolve_ggsn_got_imsi[sizeof(resolve_ggsn_got_imsi) - 1] = '\0';
+	}
+	else
+		strcpy(resolve_ggsn_got_imsi, "(null)");
+
+	if (apn_ni_str) {
+		strncpy(resolve_ggsn_got_ni, apn_ni_str, sizeof(resolve_ggsn_got_ni));
+		resolve_ggsn_got_ni[sizeof(resolve_ggsn_got_ni) - 1] = '\0';
+	}
+	else
+		strcpy(resolve_ggsn_got_ni, "(null)");
+
+	return pp;
+}
+
+#define was_resolved_for(IMSI,NI) _was_resolved_for(IMSI, NI, __FILE__, __LINE__)
+static int _was_resolved_for(const char *imsi, const char *ni, const char *file, int line)
+{
+	int cmp0 = strncmp(imsi, resolve_ggsn_got_imsi, sizeof(resolve_ggsn_got_imsi));
+
+	if (cmp0 != 0) {
+		printf("\n%s:%d: was_resolved_for(): MISMATCH for IMSI\n"
+		       "  expecting: '%s'\n"
+		       "        got: '%s'\n\n",
+		       file,
+		       line,
+		       imsi, resolve_ggsn_got_imsi);
+	}
+
+	int cmp1 = strncmp(ni, resolve_ggsn_got_ni, sizeof(resolve_ggsn_got_ni));
+	if (cmp1 != 0) {
+		printf("\n%s:%d: was_resolved_for(): MISMATCH for NI\n"
+		       "  expecting: '%s'\n"
+		       "        got: '%s'\n\n",
+		       file,
+		       line,
+		       ni, resolve_ggsn_got_ni);
+	}
+
+	return (cmp0 == 0) && (cmp1 == 0);
+}
+
+/* override, requires '-Wl,--wrap=gtphub_ares_init' */
+int __real_gtphub_ares_init(struct gtphub *hub);
+
+int __wrap_gtphub_ares_init(struct gtphub *hub)
+{
+	/* Do nothing. */
+	return 0;
 }
 
 #define buf_len 1024
@@ -413,6 +467,9 @@
 
 	gtphub_init(hub);
 
+	/* TODO This test should test for gtphub echoing back to each side.
+	 * Echos must not be routed through. */
+
 	const char *gtp_ping_from_sgsn =
 		"32"	/* 0b001'1 0010: version 1, protocol GTP, with seq nr. */
 		"01"	/* type 01: Echo request */
@@ -444,16 +501,17 @@
 		"00" "00" "0e01";
 
 	/* Set the GGSN address that gtphub is forced to resolve to. */
-	OSMO_ASSERT(osmo_sockaddr_init_udp(&resolved_ggsn_addr,
-					   "192.168.43.34", 434)
+	const char *resolved_ggsn_str = "192.168.43.34";
+	resolved_ggsn_port = 434;
+	OSMO_ASSERT(gsn_addr_from_str(&resolved_ggsn_addr, resolved_ggsn_str)
 		    == 0);
 
-	/* according to spec, we'd always send to port 2123 instead...
-	struct osmo_sockaddr ggsn_standard_port;
-	OSMO_ASSERT(osmo_sockaddr_init_udp(&ggsn_standard_port,
-					   "192.168.43.34", 2123)
+	/* A sockaddr for comparing later */
+	struct osmo_sockaddr resolved_ggsn_sa;
+	OSMO_ASSERT(osmo_sockaddr_init_udp(&resolved_ggsn_sa,
+					   resolved_ggsn_str,
+					   resolved_ggsn_port)
 		    == 0);
-	 */
 
 	struct osmo_sockaddr orig_sgsn_addr;
 	OSMO_ASSERT(osmo_sockaddr_init(&orig_sgsn_addr,
@@ -467,7 +525,7 @@
 					    &ggsn_ofd, &ggsn_addr);
 	OSMO_ASSERT(send > 0);
 	OSMO_ASSERT(ggsn_addr.l);
-	OSMO_ASSERT(same_addr(&ggsn_addr, &resolved_ggsn_addr));
+	OSMO_ASSERT(same_addr(&ggsn_addr, &resolved_ggsn_sa));
 	OSMO_ASSERT(msg_is(gtp_ping_to_ggsn));
 
 	struct osmo_fd *sgsn_ofd;
@@ -481,7 +539,7 @@
 
 	struct gtphub_peer_port *ggsn_port =
 		gtphub_port_find_sa(&hub->to_ggsns[GTPH_PLANE_CTRL],
-				    &resolved_ggsn_addr);
+				    &resolved_ggsn_sa);
 	OSMO_ASSERT(ggsn_port);
 	struct gtphub_peer *ggsn = ggsn_port->peer_addr->peer;
 	/* now == 123; now + 30 == 153. */
@@ -515,7 +573,7 @@
 	const char *gtp_req_from_sgsn =
 		"32" 	/* 0b001'1 0010: version 1, protocol GTP, with seq nr. */
 		"10" 	/* type 16: Create PDP Context Request */
-		"0067"	/* length = 8 + 103 */
+		"0068"	/* length = 8 + 104 */
 		"00000000" /* No TEI yet */
 		"abcd"	/* Sequence nr */
 		"00"	/* N-PDU 0 */
@@ -536,8 +594,8 @@
 		  "0002" /* length = 2: empty PDP Address */
 		  "f121" /* spare 0xf0, PDP organization 1, PDP type number 0x21 = 33 */
 		"83"	/* 131: Access Point Name */
-		  "0008" /* length = 8 */
-		  "696e7465726e6574" /* "internet" */
+		  "0009" /* length */
+		  "08696e7465726e6574" /* "internet" */
 		"84"	/* 132: Protocol Configuration Options */
 		  "0015" /* length = 21 */
 		  "80c0231101010011036d69670868656d6d656c6967"
@@ -557,13 +615,13 @@
 		;
 
 	const char *gtp_req_to_ggsn =
-		"32" "10" "0067" "00000000"
+		"32" "10" "0068" "00000000"
 		"6d31"	/* mapped seq ("abcd") */
 		"00" "00" "02" "42000121436587f9" "0e60" "0f01"
 		"10" "00000001" /* mapped TEI Data I ("123") */
 		"11" "00000001" /* mapped TEI Control ("321") */
 		"1400" "1a" "0800" "80" "0002" "f121" "83"
-		"0008" "696e7465726e6574" "84" "0015"
+		"0009" "08696e7465726e6574" "84" "0015"
 		"80c0231101010011036d69670868656d6d656c6967" "85" "0004"
 		"7f000201" /* replaced with gtphub's address ggsn ctrl */
 		"85" "0004"
@@ -627,14 +685,23 @@
 		;
 
 	/* Set the GGSN address that gtphub is forced to resolve to. */
-	OSMO_ASSERT(osmo_sockaddr_init_udp(&resolved_ggsn_addr,
-					   "192.168.43.34", 434)
+	const char *resolved_ggsn_str = "192.168.43.34";
+	resolved_ggsn_port = 434;
+	OSMO_ASSERT(gsn_addr_from_str(&resolved_ggsn_addr, resolved_ggsn_str)
+		    == 0);
+
+	/* A sockaddr for comparing later */
+	struct osmo_sockaddr resolved_ggsn_sa;
+	OSMO_ASSERT(osmo_sockaddr_init_udp(&resolved_ggsn_sa,
+					   resolved_ggsn_str,
+					   resolved_ggsn_port)
 		    == 0);
 
 	struct osmo_sockaddr orig_sgsn_addr;
 	OSMO_ASSERT(osmo_sockaddr_init(&orig_sgsn_addr,
 				       AF_UNSPEC, SOCK_DGRAM, IPPROTO_UDP,
 				       "192.168.42.23", 423) == 0);
+
 	struct osmo_fd *ggsn_ofd = NULL;
 	struct osmo_sockaddr ggsn_addr;
 	int send;
@@ -642,8 +709,9 @@
 					    buf, msg(gtp_req_from_sgsn), now,
 					    &ggsn_ofd, &ggsn_addr);
 	OSMO_ASSERT(send > 0);
-	OSMO_ASSERT(same_addr(&ggsn_addr, &resolved_ggsn_addr));
+	OSMO_ASSERT(same_addr(&ggsn_addr, &resolved_ggsn_sa));
 	OSMO_ASSERT(msg_is(gtp_req_to_ggsn));
+	OSMO_ASSERT(was_resolved_for("240010123456789", "internet"));
 
 	struct osmo_fd *sgsn_ofd;
 	struct osmo_sockaddr sgsn_addr;
@@ -656,7 +724,7 @@
 
 	struct gtphub_peer_port *ggsn_port =
 		gtphub_port_find_sa(&hub->to_ggsns[GTPH_PLANE_CTRL],
-				    &resolved_ggsn_addr);
+				    &resolved_ggsn_sa);
 	OSMO_ASSERT(ggsn_port);
 	struct gtphub_peer *ggsn = ggsn_port->peer_addr->peer;
 	/* now == 345; now + 30 == 375.
diff --git a/openbsc/tests/gtphub/gtphub_test.ok b/openbsc/tests/gtphub/gtphub_test.ok
index 7be13fe..8d1075a 100644
--- a/openbsc/tests/gtphub/gtphub_test.ok
+++ b/openbsc/tests/gtphub/gtphub_test.ok
@@ -1,3 +1,3 @@
-Wrap: returning GGSN addr: 192.168.43.34 port 434
-Wrap: returning GGSN addr: 192.168.43.34 port 434
+Wrap: returning GGSN addr from imsi (null) ni (null): 192.168.43.34 port 434
+Wrap: returning GGSN addr from imsi 240010123456789 ni internet: 192.168.43.34 port 434
 Done