diff --git a/openbsc/include/openbsc/gprs_sgsn.h b/openbsc/include/openbsc/gprs_sgsn.h
index 3e80ae2..b135813 100644
--- a/openbsc/include/openbsc/gprs_sgsn.h
+++ b/openbsc/include/openbsc/gprs_sgsn.h
@@ -287,8 +287,23 @@
 enum sgsn_auth_state sgsn_auth_state(struct sgsn_mm_ctx *mm);
 void sgsn_auth_update(struct sgsn_mm_ctx *mm);
 
+/*
+ * GPRS subscriber data
+ */
+#define GPRS_SUBSCRIBER_UPDATE_PENDING (1 << 16)
+#define GPRS_SUBSCRIBER_CANCELLED      (1 << 17)
+
+void gprs_subscr_init(struct sgsn_instance *sgi);
+int gprs_subscr_request_update(struct sgsn_mm_ctx *mmctx);
+void gprs_subscr_delete(struct gsm_subscriber *subscr);
+struct gsm_subscriber *gprs_subscr_get_or_create(const char *imsi);
+struct gsm_subscriber *gprs_subscr_get_by_imsi(const char *imsi);
+void gprs_subscr_put_and_cancel(struct gsm_subscriber *subscr);
+void gprs_subscr_update(struct gsm_subscriber *subscr);
+
 /* Called on subscriber data updates */
-void sgsn_update_subscriber_data(struct sgsn_mm_ctx *mmctx);
+void sgsn_update_subscriber_data(struct sgsn_mm_ctx *mmctx,
+				 struct gsm_subscriber *subscr);
 
 int gprs_sndcp_vty_init(void);
 struct sgsn_instance;
diff --git a/openbsc/include/openbsc/gsm_subscriber.h b/openbsc/include/openbsc/gsm_subscriber.h
index 46fc87f..195fa0f 100644
--- a/openbsc/include/openbsc/gsm_subscriber.h
+++ b/openbsc/include/openbsc/gsm_subscriber.h
@@ -13,6 +13,7 @@
 #define GSM_MAX_EXTEN 49999
 
 #define GSM_SUBSCRIBER_FIRST_CONTACT	0x00000001
+/* gprs_sgsn.h defines additional flags including and above bit 16 (0x10000) */
 #define tmsi_from_string(str) strtoul(str, NULL, 10)
 
 #define GSM_SUBSCRIBER_NO_EXPIRATION	0x0
diff --git a/openbsc/src/gprs/Makefile.am b/openbsc/src/gprs/Makefile.am
index 75eafdd..f937362 100644
--- a/openbsc/src/gprs/Makefile.am
+++ b/openbsc/src/gprs/Makefile.am
@@ -22,7 +22,7 @@
 osmo_sgsn_SOURCES =	gprs_gmm.c gprs_sgsn.c gprs_sndcp.c gprs_sndcp_vty.c \
 			sgsn_main.c sgsn_vty.c sgsn_libgtp.c \
 			gprs_llc.c gprs_llc_parse.c gprs_llc_vty.c crc24.c \
-			sgsn_ctrl.c sgsn_auth.c
+			sgsn_ctrl.c sgsn_auth.c gprs_subscriber.c
 osmo_sgsn_LDADD = 	\
 			$(top_builddir)/src/libcommon/libcommon.a \
 			-lgtp $(OSMO_LIBS) $(LIBOSMOABIS_LIBS)
diff --git a/openbsc/src/gprs/gprs_sgsn.c b/openbsc/src/gprs/gprs_sgsn.c
index 39bfa84..71cd742 100644
--- a/openbsc/src/gprs/gprs_sgsn.c
+++ b/openbsc/src/gprs/gprs_sgsn.c
@@ -452,7 +452,8 @@
 	return gsm0408_gprs_force_reattach_oldmsg(oldmsg);
 }
 
-void sgsn_update_subscriber_data(struct sgsn_mm_ctx *mmctx)
+void sgsn_update_subscriber_data(struct sgsn_mm_ctx *mmctx,
+				 struct gsm_subscriber *subscr)
 {
 	OSMO_ASSERT(mmctx);
 
diff --git a/openbsc/src/gprs/gprs_subscriber.c b/openbsc/src/gprs/gprs_subscriber.c
new file mode 100644
index 0000000..78fa3e1
--- /dev/null
+++ b/openbsc/src/gprs/gprs_subscriber.c
@@ -0,0 +1,144 @@
+/* MS subscriber data handling */
+
+/* (C) 2014 by sysmocom s.f.m.c. GmbH
+ *
+ * All Rights Reserved
+ *
+ * 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/gsm_subscriber.h>
+
+#include <openbsc/sgsn.h>
+#include <openbsc/gprs_sgsn.h>
+#include <openbsc/gprs_gmm.h>
+
+#include <openbsc/debug.h>
+
+extern void *tall_bsc_ctx;
+
+void gprs_subscr_init(struct sgsn_instance *sgi)
+{
+}
+
+struct gsm_subscriber *gprs_subscr_get_or_create(const char *imsi)
+{
+	struct gsm_subscriber *subscr;
+
+	subscr = subscr_get_or_create(NULL, imsi);
+	if (!subscr)
+		return NULL;
+
+	subscr->keep_in_ram = 1;
+
+	return subscr;
+}
+
+struct gsm_subscriber *gprs_subscr_get_by_imsi(const char *imsi)
+{
+	return subscr_active_by_imsi(NULL, imsi);
+}
+
+void gprs_subscr_delete(struct gsm_subscriber *subscr)
+{
+	if (subscr->mm) {
+		subscr_put(subscr->mm->subscr);
+		subscr->mm->subscr = NULL;
+		subscr->mm = NULL;
+	}
+
+	if ((subscr->flags & GPRS_SUBSCRIBER_CANCELLED) ||
+	    (subscr->flags & GSM_SUBSCRIBER_FIRST_CONTACT))
+		subscr->keep_in_ram = 0;
+
+	subscr_put(subscr);
+}
+
+void gprs_subscr_put_and_cancel(struct gsm_subscriber *subscr)
+{
+	subscr->authorized = 0;
+	subscr->flags |= GPRS_SUBSCRIBER_CANCELLED;
+
+	gprs_subscr_update(subscr);
+
+	gprs_subscr_delete(subscr);
+}
+
+int gprs_subscr_query(struct gsm_subscriber *subscr)
+{
+	/* TODO: Implement remote query to MSC, ... */
+
+	LOGMMCTXP(LOGL_INFO, subscr->mm,
+		  "subscriber data is not available (remote query NYI)\n");
+	return -ENOTSUP;
+}
+
+void gprs_subscr_update(struct gsm_subscriber *subscr)
+{
+	LOGMMCTXP(LOGL_DEBUG, subscr->mm, "Updating subscriber data\n");
+
+	subscr->flags &= ~GPRS_SUBSCRIBER_UPDATE_PENDING;
+	subscr->flags &= ~GSM_SUBSCRIBER_FIRST_CONTACT;
+
+	sgsn_update_subscriber_data(subscr->mm, subscr);
+}
+
+int gprs_subscr_request_update(struct sgsn_mm_ctx *mmctx)
+{
+	struct gsm_subscriber *subscr = NULL;
+	int need_update = 0;
+	int rc;
+
+	LOGMMCTXP(LOGL_DEBUG, mmctx, "Requesting subscriber data update\n");
+
+	if (mmctx->subscr) {
+		subscr = subscr_get(mmctx->subscr);
+	} else if (mmctx->imsi[0]) {
+		subscr = gprs_subscr_get_by_imsi(mmctx->imsi);
+		need_update = 1;
+	}
+
+	if (!subscr) {
+		subscr = gprs_subscr_get_or_create(mmctx->imsi);
+		subscr->flags |= GSM_SUBSCRIBER_FIRST_CONTACT;
+		need_update = 1;
+	}
+
+	if (strcpy(subscr->equipment.imei, mmctx->imei) != 0) {
+		strncpy(subscr->equipment.imei, mmctx->imei, GSM_IMEI_LENGTH-1);
+		subscr->equipment.imei[GSM_IMEI_LENGTH-1] = 0;
+		need_update = 1;
+	}
+
+	if (subscr->lac != mmctx->ra.lac) {
+		subscr->lac = mmctx->ra.lac;
+		need_update = 1;
+	}
+
+	if (need_update) {
+		subscr->flags |= GPRS_SUBSCRIBER_UPDATE_PENDING;
+		if (!mmctx->subscr) {
+			subscr->mm = mmctx;
+			mmctx->subscr = subscr_get(subscr);
+		}
+
+		rc = gprs_subscr_query(subscr);
+		subscr_put(subscr);
+		return rc;
+	}
+	gprs_subscr_update(subscr);
+	subscr_put(subscr);
+	return 0;
+}
diff --git a/openbsc/src/gprs/sgsn_main.c b/openbsc/src/gprs/sgsn_main.c
index 0310cb2..141eacf 100644
--- a/openbsc/src/gprs/sgsn_main.c
+++ b/openbsc/src/gprs/sgsn_main.c
@@ -58,9 +58,6 @@
 
 #include "../../bscconfig.h"
 
-/* this is here for the vty... it will never be called */
-void subscr_put() { abort(); }
-
 #define _GNU_SOURCE
 #include <getopt.h>
 
diff --git a/openbsc/tests/sgsn/Makefile.am b/openbsc/tests/sgsn/Makefile.am
index f822aac..0e5d009 100644
--- a/openbsc/tests/sgsn/Makefile.am
+++ b/openbsc/tests/sgsn/Makefile.am
@@ -6,6 +6,9 @@
 noinst_PROGRAMS = sgsn_test
 
 sgsn_test_SOURCES = sgsn_test.c
+sgsn_test_LDFLAGS = \
+	-Wl,--wrap=sgsn_update_subscriber_data
+
 sgsn_test_LDADD = \
 	$(top_builddir)/src/gprs/gprs_llc_parse.o \
 	$(top_builddir)/src/gprs/gprs_llc.o \
@@ -16,6 +19,8 @@
 	$(top_builddir)/src/gprs/sgsn_vty.o \
 	$(top_builddir)/src/gprs/sgsn_libgtp.o \
 	$(top_builddir)/src/gprs/sgsn_auth.o \
+	$(top_builddir)/src/gprs/gprs_subscriber.o \
+	$(top_builddir)/src/libcommon/libcommon.a \
 	$(LIBOSMOCORE_LIBS) \
 	$(LIBOSMOGSM_LIBS) \
 	$(LIBOSMOGB_LIBS) \
diff --git a/openbsc/tests/sgsn/sgsn_test.c b/openbsc/tests/sgsn/sgsn_test.c
index 533c393..2eb6f38 100644
--- a/openbsc/tests/sgsn/sgsn_test.c
+++ b/openbsc/tests/sgsn/sgsn_test.c
@@ -23,6 +23,7 @@
 #include <openbsc/sgsn.h>
 #include <openbsc/gprs_gmm.h>
 #include <openbsc/debug.h>
+#include <openbsc/gsm_subscriber.h>
 
 #include <osmocom/gprs/gprs_bssgp.h>
 
@@ -55,6 +56,18 @@
 	return 0;
 }
 
+/* override, requires '-Wl,--wrap=sgsn_update_subscriber_data' */
+void __real_sgsn_update_subscriber_data(struct sgsn_mm_ctx *, struct gsm_subscriber *);
+void (*update_subscriber_data_cb)(struct sgsn_mm_ctx *, struct gsm_subscriber *) =
+    &__real_sgsn_update_subscriber_data;
+
+void __wrap_sgsn_update_subscriber_data(struct sgsn_mm_ctx *mmctx,
+					struct gsm_subscriber *subscr)
+{
+	(*update_subscriber_data_cb)(mmctx, subscr);
+}
+
+
 static int count(struct llist_head *head)
 {
 	struct llist_head *cur;
@@ -146,6 +159,88 @@
 	OSMO_ASSERT(count(gprs_llme_list()) == 0);
 }
 
+struct gsm_subscriber *last_updated_subscr = NULL;
+void my_dummy_sgsn_update_subscriber_data(struct sgsn_mm_ctx *mmctx,
+					  struct gsm_subscriber *subscr)
+{
+	fprintf(stderr, "Called %s, mmctx = %p, subscr = %p\n",
+		__func__, mmctx, subscr);
+	last_updated_subscr = subscr;
+}
+
+static void test_subscriber(void)
+{
+	struct gsm_subscriber *s1, *s2, *s1found, *s2found;
+	const char *imsi1 = "1234567890";
+	const char *imsi2 = "9876543210";
+
+	update_subscriber_data_cb = my_dummy_sgsn_update_subscriber_data;
+
+	printf("Testing core subscriber data API\n");
+
+	/* Check for emptiness */
+	OSMO_ASSERT(gprs_subscr_get_by_imsi(imsi1) == NULL);
+	OSMO_ASSERT(gprs_subscr_get_by_imsi(imsi2) == NULL);
+
+	/* Allocate entry 1 */
+	s1 = gprs_subscr_get_or_create(imsi1);
+	s1->flags |= GSM_SUBSCRIBER_FIRST_CONTACT;
+	s1found = gprs_subscr_get_by_imsi(imsi1);
+	OSMO_ASSERT(s1found == s1);
+	OSMO_ASSERT(gprs_subscr_get_by_imsi(imsi2) == NULL);
+	subscr_put(s1found);
+
+	/* Allocate entry 2 */
+	s2 = gprs_subscr_get_or_create(imsi2);
+	s2->flags |= GSM_SUBSCRIBER_FIRST_CONTACT;
+	s1found = gprs_subscr_get_by_imsi(imsi1);
+	s2found = gprs_subscr_get_by_imsi(imsi2);
+	OSMO_ASSERT(s1found == s1);
+	OSMO_ASSERT(s2found == s2);
+	subscr_put(s1found);
+	subscr_put(s2found);
+
+	/* Update entry 1 */
+	last_updated_subscr = NULL;
+	gprs_subscr_update(s1);
+	OSMO_ASSERT(last_updated_subscr == s1);
+
+	/* Because of the update, it won't be freed on delete now */
+	gprs_subscr_delete(s1);
+	s1found = gprs_subscr_get_by_imsi(imsi1);
+	OSMO_ASSERT(s1found != NULL);
+	s1 = s1found;
+
+	/* Cancel it, so that delete will free it.
+	 * Refcount it to make sure s1 won't be freed here */
+	last_updated_subscr = NULL;
+	gprs_subscr_put_and_cancel(subscr_get(s1));
+	OSMO_ASSERT(last_updated_subscr == s1);
+
+	/* Cancelled entries are still being found */
+	s1found = gprs_subscr_get_by_imsi(imsi1);
+	OSMO_ASSERT(s1found != NULL);
+	subscr_put(s1found);
+
+	/* Free entry 1 */
+	gprs_subscr_delete(s1);
+	s1 = NULL;
+	s2found = gprs_subscr_get_by_imsi(imsi2);
+	OSMO_ASSERT(gprs_subscr_get_by_imsi(imsi1) == NULL);
+	OSMO_ASSERT(s2found == s2);
+	subscr_put(s2found);
+
+	/* Free entry 2 */
+	gprs_subscr_delete(s2);
+	s2 = NULL;
+	OSMO_ASSERT(gprs_subscr_get_by_imsi(imsi1) == NULL);
+	OSMO_ASSERT(gprs_subscr_get_by_imsi(imsi2) == NULL);
+
+	OSMO_ASSERT(llist_empty(&active_subscribers));
+
+	update_subscriber_data_cb = __real_sgsn_update_subscriber_data;
+}
+
 /*
  * Test that a GMM Detach will remove the MMCTX and the
  * associated LLME.
@@ -778,7 +873,6 @@
 	sgsn->cfg.auth_policy = saved_auth_policy;
 }
 
-
 static struct log_info_cat gprs_categories[] = {
 	[DMM] = {
 		.name = "DMM",
@@ -841,8 +935,10 @@
 	tall_msgb_ctx = talloc_named_const(tall_bsc_ctx, 0, "msgb");
 
 	sgsn_auth_init();
+	gprs_subscr_init(sgsn);
 
 	test_llme();
+	test_subscriber();
 	test_gmm_detach();
 	test_gmm_detach_power_off();
 	test_gmm_detach_no_mmctx();
diff --git a/openbsc/tests/sgsn/sgsn_test.ok b/openbsc/tests/sgsn/sgsn_test.ok
index db96311..1ee80be 100644
--- a/openbsc/tests/sgsn/sgsn_test.ok
+++ b/openbsc/tests/sgsn/sgsn_test.ok
@@ -1,4 +1,5 @@
 Testing LLME allocations
+Testing core subscriber data API
 Testing GMM detach
 Testing GMM detach (power off)
 Testing GMM detach (no MMCTX)