diff --git a/src/gb/Makefile.am b/src/gb/Makefile.am
index 7248413..125afba 100644
--- a/src/gb/Makefile.am
+++ b/src/gb/Makefile.am
@@ -7,7 +7,7 @@
 AM_CFLAGS = -Wall ${GCC_FVISIBILITY_HIDDEN} -fno-strict-aliasing $(TALLOC_CFLAGS)
 
 # FIXME: this should eventually go into a milenage/Makefile.am
-noinst_HEADERS = common_vty.h gb_internal.h
+noinst_HEADERS = common_vty.h gb_internal.h gprs_bssgp_internal.h
 
 if ENABLE_GB
 lib_LTLIBRARIES = libosmogb.la
diff --git a/src/gb/gprs_bssgp.c b/src/gb/gprs_bssgp.c
index 38794c2..fa4e187 100644
--- a/src/gb/gprs_bssgp.c
+++ b/src/gb/gprs_bssgp.c
@@ -44,6 +44,11 @@
 
 void *bssgp_tall_ctx = NULL;
 
+static int _gprs_ns_sendmsg(void *ctx, struct msgb *msg);
+
+bssgp_bvc_send bssgp_ns_send = _gprs_ns_sendmsg;
+void *bssgp_ns_send_data = NULL;
+
 static const struct rate_ctr_desc bssgp_ctr_description[] = {
 	{ "packets:in",	"Packets at BSSGP Level ( In)" },
 	{ "packets:out","Packets at BSSGP Level (Out)" },
@@ -67,6 +72,13 @@
 static int _bssgp_tx_dl_ud(struct bssgp_flow_control *fc, struct msgb *msg,
 			   uint32_t llc_pdu_len, void *priv);
 
+
+/* callback to be backward compatible with  old users which do not set the bssgp_ns_send function */
+static int _gprs_ns_sendmsg(void *ctx, struct msgb *msg)
+{
+	return gprs_ns_sendmsg(bssgp_nsi, msg);
+}
+
 /* Find a BTS Context based on parsed RA ID and Cell ID */
 struct bssgp_bvc_ctx *btsctx_by_raid_cid(const struct gprs_ra_id *raid, uint16_t cid)
 {
@@ -117,6 +129,12 @@
 	return NULL;
 }
 
+void bssgp_set_bssgp_callback(bssgp_bvc_send ns_send, void *data)
+{
+	bssgp_ns_send = ns_send;
+	bssgp_ns_send_data = data;
+}
+
 struct bssgp_bvc_ctx *btsctx_alloc(uint16_t bvci, uint16_t nsei)
 {
 	struct bssgp_bvc_ctx *ctx;
@@ -163,7 +181,7 @@
 	bgph->pdu_type = BSSGP_PDUT_FLOW_CONTROL_BVC_ACK;
 	msgb_tvlv_put(msg, BSSGP_IE_TAG, 1, &tag);
 
-	return gprs_ns_sendmsg(bssgp_nsi, msg);
+	return bssgp_ns_send(bssgp_ns_send_data, msg);
 }
 
 /* 10.3.7 SUSPEND-ACK PDU */
@@ -182,7 +200,7 @@
 	bssgp_msgb_ra_put(msg, ra_id);
 	msgb_tvlv_put(msg, BSSGP_IE_SUSPEND_REF_NR, 1, &suspend_ref);
 
-	return gprs_ns_sendmsg(bssgp_nsi, msg);
+	return bssgp_ns_send(bssgp_ns_send_data, msg);
 }
 
 /* 10.3.8 SUSPEND-NACK PDU */
@@ -204,7 +222,7 @@
 	if (cause)
 		msgb_tvlv_put(msg, BSSGP_IE_CAUSE, 1, cause);
 
-	return gprs_ns_sendmsg(bssgp_nsi, msg);
+	return bssgp_ns_send(bssgp_ns_send_data, msg);
 }
 
 /* 10.3.10 RESUME-ACK PDU */
@@ -222,7 +240,7 @@
 	bssgp_msgb_tlli_put(msg, tlli);
 	bssgp_msgb_ra_put(msg, ra_id);
 
-	return gprs_ns_sendmsg(bssgp_nsi, msg);
+	return bssgp_ns_send(bssgp_ns_send_data, msg);
 }
 
 /* 10.3.11 RESUME-NACK PDU */
@@ -243,7 +261,7 @@
 	if (cause)
 		msgb_tvlv_put(msg, BSSGP_IE_CAUSE, 1, cause);
 
-	return gprs_ns_sendmsg(bssgp_nsi, msg);
+	return bssgp_ns_send(bssgp_ns_send_data, msg);
 }
 
 uint16_t bssgp_parse_cell_id(struct gprs_ra_id *raid, const uint8_t *buf)
@@ -266,7 +284,7 @@
 }
 
 /* Chapter 8.4 BVC-Reset Procedure */
-static int bssgp_rx_bvc_reset(struct msgb *msg, struct tlv_parsed *tp,	
+static int bssgp_rx_bvc_reset(struct msgb *msg, struct tlv_parsed *tp,
 			      uint16_t ns_bvci)
 {
 	struct osmo_bssgp_prim nmp;
@@ -744,7 +762,7 @@
 static int _bssgp_tx_dl_ud(struct bssgp_flow_control *fc, struct msgb *msg,
 			   uint32_t llc_pdu_len, void *priv)
 {
-	return gprs_ns_sendmsg(bssgp_nsi, msg);
+	return bssgp_ns_send(bssgp_ns_send_data, msg);
 }
 
 /* input function of the flow control implementation, called first
@@ -1286,7 +1304,7 @@
 		msgb_tvlv_put(msg, BSSGP_IE_TMSI, 4, (uint8_t *) &ptmsi);
 	}
 
-	return gprs_ns_sendmsg(bssgp_nsi, msg);
+	return bssgp_ns_send(bssgp_ns_send_data, msg);
 }
 
 void bssgp_set_log_ss(int ss)
diff --git a/src/gb/gprs_bssgp_bss.c b/src/gb/gprs_bssgp_bss.c
index 5a1ffb9..94b1812 100644
--- a/src/gb/gprs_bssgp_bss.c
+++ b/src/gb/gprs_bssgp_bss.c
@@ -34,6 +34,7 @@
 #include <osmocom/gprs/gprs_bssgp_bss.h>
 #include <osmocom/gprs/gprs_ns.h>
 
+#include "gprs_bssgp_internal.h"
 #include "common_vty.h"
 
 #define GSM_IMSI_LENGTH 17
@@ -69,7 +70,7 @@
 	bssgp_msgb_tlli_put(msg, tlli);
 	bssgp_msgb_ra_put(msg, ra_id);
 
-	return gprs_ns_sendmsg(bssgp_nsi, msg);
+	return bssgp_ns_send(bssgp_ns_send_data, msg);
 }
 
 /*! GMM-RESUME.req (Chapter 10.3.9) */
@@ -91,7 +92,7 @@
 
 	msgb_tvlv_put(msg, BSSGP_IE_SUSPEND_REF_NR, 1, &suspend_ref);
 
-	return gprs_ns_sendmsg(bssgp_nsi, msg);
+	return bssgp_ns_send(bssgp_ns_send_data, msg);
 }
 
 /*! Transmit RA-CAPABILITY-UPDATE (10.3.3) */
@@ -113,7 +114,7 @@
 
 	msgb_tvlv_put(msg, BSSGP_IE_TAG, 1, &tag);
 
-	return gprs_ns_sendmsg(bssgp_nsi, msg);
+	return bssgp_ns_send(bssgp_ns_send_data, msg);
 }
 
 /* first common part of RADIO-STATUS */
@@ -141,7 +142,7 @@
 	msgb_tvlv_put(msg, BSSGP_IE_CAUSE, 1, &cause);
 	LOGPC(DBSSGP, LOGL_NOTICE, "CAUSE=%s\n", bssgp_cause_str(cause));
 
-	return gprs_ns_sendmsg(bssgp_nsi, msg);
+	return bssgp_ns_send(bssgp_ns_send_data, msg);
 }
 
 /*! Transmit RADIO-STATUS for TLLI (10.3.5) */
@@ -220,7 +221,7 @@
 		msgb_tvlv_put(msg, BSSGP_IE_BVCI, 2, (uint8_t *) &_bvci_new);
 	msgb_tvlv_put(msg, BSSGP_IE_NUM_OCT_AFF, 3, (uint8_t *) &_oct_aff);
 
-	return gprs_ns_sendmsg(bssgp_nsi, msg);
+	return bssgp_ns_send(bssgp_ns_send_data, msg);
 }
 
 /*! Transmit LLC-DISCARDED (Chapter 10.4.3) */
@@ -246,7 +247,7 @@
 	msgb_tvlv_put(msg, BSSGP_IE_BVCI, 2, (uint8_t *) &_bvci);
 	msgb_tvlv_put(msg, BSSGP_IE_NUM_OCT_AFF, 3, ((uint8_t *) &_oct_aff) + 1);
 
-	return gprs_ns_sendmsg(bssgp_nsi, msg);
+	return bssgp_ns_send(bssgp_ns_send_data, msg);
 }
 
 /*! Transmit a BVC-BLOCK message (Chapter 10.4.8) */
@@ -267,7 +268,7 @@
 	msgb_tvlv_put(msg, BSSGP_IE_BVCI, 2, (uint8_t *) &_bvci);
 	msgb_tvlv_put(msg, BSSGP_IE_CAUSE, 1, &cause);
 
-	return gprs_ns_sendmsg(bssgp_nsi, msg);
+	return bssgp_ns_send(bssgp_ns_send_data, msg);
 }
 
 /*! Transmit a BVC-UNBLOCK message (Chapter 10.4.10) */
@@ -286,7 +287,7 @@
 
 	msgb_tvlv_put(msg, BSSGP_IE_BVCI, 2, (uint8_t *) &_bvci);
 
-	return gprs_ns_sendmsg(bssgp_nsi, msg);
+	return bssgp_ns_send(bssgp_ns_send_data, msg);
 }
 
 /*! Transmit a BVC-RESET message (Chapter 10.4.12) */
@@ -313,7 +314,7 @@
 	}
 	/* Optional: Feature Bitmap */
 
-	return gprs_ns_sendmsg(bssgp_nsi, msg);
+	return bssgp_ns_send(bssgp_ns_send_data, msg);
 }
 int bssgp_tx_bvc_reset(struct bssgp_bvc_ctx *bctx, uint16_t bvci, uint8_t cause)
 {
@@ -389,7 +390,7 @@
 			      sizeof(e_queue_delay),
 			      (uint8_t *) &e_queue_delay);
 
-	return gprs_ns_sendmsg(bssgp_nsi, msg);
+	return bssgp_ns_send(bssgp_ns_send_data, msg);
 }
 
 /*! Transmit a FLOW_CONTROL-MS (Chapter 10.4.6)
@@ -432,7 +433,7 @@
 		msgb_tvlv_put(msg, BSSGP_IE_BUCKET_FULL_RATIO,
 			      1, bucket_full_ratio);
 
-	return gprs_ns_sendmsg(bssgp_nsi, msg);
+	return bssgp_ns_send(bssgp_ns_send_data, msg);
 }
 
 /*! RL-UL-UNITDATA.req (Chapter 10.2.2)
@@ -478,7 +479,7 @@
 	rate_ctr_inc(&bctx->ctrg->ctr[BSSGP_CTR_PKTS_OUT]);
 	rate_ctr_add(&bctx->ctrg->ctr[BSSGP_CTR_BYTES_OUT], msg->len);
 
-	return gprs_ns_sendmsg(bssgp_nsi, msg);
+	return bssgp_ns_send(bssgp_ns_send_data, msg);
 }
 
 /* Parse a single GMM-PAGING.req to a given NSEI/NS-BVCI */
diff --git a/src/gb/gprs_bssgp_internal.h b/src/gb/gprs_bssgp_internal.h
new file mode 100644
index 0000000..2ada027
--- /dev/null
+++ b/src/gb/gprs_bssgp_internal.h
@@ -0,0 +1,7 @@
+
+#pragma once
+
+#include <osmocom/gprs/gprs_bssgp.h>
+
+extern bssgp_bvc_send bssgp_ns_send;
+extern void *bssgp_ns_send_data;
diff --git a/src/gb/gprs_bssgp_util.c b/src/gb/gprs_bssgp_util.c
index 7708949..917f1f3 100644
--- a/src/gb/gprs_bssgp_util.c
+++ b/src/gb/gprs_bssgp_util.c
@@ -32,6 +32,7 @@
 #include <osmocom/gprs/gprs_bssgp.h>
 #include <osmocom/gprs/gprs_ns.h>
 
+#include "gprs_bssgp_internal.h"
 #include "common_vty.h"
 
 struct gprs_ns_inst *bssgp_nsi;
@@ -210,7 +211,7 @@
 	_bvci = osmo_htons(bvci);
 	msgb_tvlv_put(msg, BSSGP_IE_BVCI, 2, (uint8_t *) &_bvci);
 
-	return gprs_ns_sendmsg(bssgp_nsi, msg);
+	return bssgp_ns_send(bssgp_ns_send_data, msg);
 }
 
 /* Chapter 10.4.14: Status */
@@ -248,5 +249,5 @@
 	msgb_tvlv_put(msg, BSSGP_IE_PDU_IN_ERROR,
 		      msgb_bssgp_len(orig_msg), msgb_bssgph(orig_msg));
 
-	return gprs_ns_sendmsg(bssgp_nsi, msg);
+	return bssgp_ns_send(bssgp_ns_send_data, msg);
 }
diff --git a/src/gb/libosmogb.map b/src/gb/libosmogb.map
index 7a231db..0c0c5c4 100644
--- a/src/gb/libosmogb.map
+++ b/src/gb/libosmogb.map
@@ -13,6 +13,7 @@
 bssgp_msgb_tlli_put;
 bssgp_msgb_ra_put;
 bssgp_parse_cell_id;
+bssgp_set_bssgp_callback;
 bssgp_tx_bvc_block;
 bssgp_tx_bvc_reset;
 bssgp_tx_bvc_reset2;