diff --git a/openbsc/include/openbsc/Makefile.am b/openbsc/include/openbsc/Makefile.am
index d42f775d9..5f7de1aef 100644
--- a/openbsc/include/openbsc/Makefile.am
+++ b/openbsc/include/openbsc/Makefile.am
@@ -18,7 +18,8 @@ noinst_HEADERS = abis_nm.h abis_rsl.h db.h gsm_04_08.h gsm_data.h \
 		 gprs_gb_parse.h smpp.h meas_feed.h gprs_gsup_messages.h \
 		 gprs_gsup_client.h bsc_msg_filter.h \
 		 oap.h oap_messages.h \
-		 gtphub.h
+		 gtphub.h \
+		 iu.h
 
 openbsc_HEADERS = gsm_04_08.h meas_rep.h bsc_api.h
 openbscdir = $(includedir)/openbsc
diff --git a/openbsc/include/openbsc/gprs_gmm.h b/openbsc/include/openbsc/gprs_gmm.h
index e0d8f7781..b4df65092 100644
--- a/openbsc/include/openbsc/gprs_gmm.h
+++ b/openbsc/include/openbsc/gprs_gmm.h
@@ -11,6 +11,8 @@ int gsm48_tx_gsm_act_pdp_acc(struct sgsn_pdp_ctx *pdp);
 int gsm48_tx_gsm_deact_pdp_acc(struct sgsn_pdp_ctx *pdp);
 
 int gsm0408_gprs_rcvmsg_gb(struct msgb *msg, struct gprs_llc_llme *llme);
+int gsm0408_gprs_rcvmsg_iu(struct msgb *msg, struct gprs_ra_id *ra_id,
+			   uint16_t *sai);
 int gsm0408_gprs_force_reattach(struct sgsn_mm_ctx *mmctx);
 int gsm0408_gprs_force_reattach_oldmsg(struct msgb *msg);
 void gsm0408_gprs_access_granted(struct sgsn_mm_ctx *mmctx);
diff --git a/openbsc/include/openbsc/iu.h b/openbsc/include/openbsc/iu.h
new file mode 100644
index 000000000..b9d55877b
--- /dev/null
+++ b/openbsc/include/openbsc/iu.h
@@ -0,0 +1,9 @@
+#pragma once
+
+struct msgb;
+struct gprs_ra_id;
+
+typedef int (* iu_recv_cb_t )(struct msgb *msg, struct gprs_ra_id *ra_id,
+			      uint16_t *sai);
+
+int iu_tx(struct msgb *msg, uint8_t sapi);
diff --git a/openbsc/src/gprs/gprs_gmm.c b/openbsc/src/gprs/gprs_gmm.c
index cf0d3ecb5..56d892f3a 100644
--- a/openbsc/src/gprs/gprs_gmm.c
+++ b/openbsc/src/gprs/gprs_gmm.c
@@ -55,6 +55,7 @@
 #include <openbsc/gprs_utils.h>
 #include <openbsc/sgsn.h>
 #include <openbsc/signal.h>
+#include <openbsc/iu.h>
 
 #include <pdp.h>
 
@@ -138,7 +139,7 @@ static int gsm48_gmm_sendmsg(struct msgb *msg, int command,
 		rate_ctr_inc(&mm->ctrg->ctr[GMM_CTR_PKTS_SIG_OUT]);
 
 	if (msg->dst)
-		return gprs_iu_tx(msg, GPRS_SAPI_GMM, mm);
+		return iu_tx(msg, GPRS_SAPI_GMM);
 
 	/* caller needs to provide TLLI, BVCI and NSEI */
 	return gprs_llc_tx_ui(msg, GPRS_SAPI_GMM, command, mm);
diff --git a/openbsc/src/gprs/sgsn_iu.c b/openbsc/src/gprs/sgsn_iu.c
index 388f65935..edd31ffe6 100644
--- a/openbsc/src/gprs/sgsn_iu.c
+++ b/openbsc/src/gprs/sgsn_iu.c
@@ -18,14 +18,21 @@
 #include <osmocom/sigtran/sccp_sap.h>
 
 #include <openbsc/gprs_sgsn.h>
+#include <openbsc/iu.h>
 #include <openbsc/debug.h>
 
 #include <osmocom/ranap/ranap_ies_defs.h>
+#include <osmocom/ranap/ranap_common.h>
 #include <osmocom/ranap/ranap_common_cn.h>
+#include <osmocom/ranap/ranap_msg_factory.h>
+
+#include <asn1c/asn1helpers.h>
 
 int asn1_xer_print = 1;
 void *talloc_asn1_ctx;
 
+iu_recv_cb_t global_iu_recv_cb = NULL;
+
 struct ue_conn_ctx {
 	struct llist_head list;
 	struct osmo_sua_link *link;
@@ -125,6 +132,7 @@ int gprs_transp_upd_key(struct sgsn_mm_ctx *mm)
 	return 0;
 }
 
+
 static int ranap_handle_co_initial_ue(void *ctx, RANAP_InitialUE_MessageIEs_t *ies)
 {
 	struct gprs_ra_id ra_id;
@@ -138,7 +146,8 @@ static int ranap_handle_co_initial_ue(void *ctx, RANAP_InitialUE_MessageIEs_t *i
 
 	/* Feed into the MM layer */
 	msg->dst = ctx;
-	gsm0408_gprs_rcvmsg_iu(msg, ra_id, sai);
+	global_iu_recv_cb(msg, &ra_id, sai);
+	//	gsm0408_gprs_rcvmsg_iu(msg, ra_id, sai);
 
 	return 0;
 }
@@ -182,7 +191,7 @@ static int ranap_handle_co_err_ind(void *ctx, RANAP_ErrorIndicationIEs_t *ies)
 	return 0;
 }
 
-int gprs_iu_tx(struct msgb *msg, uint8_t sapi, struct mm_context *mm)
+int iu_tx(struct msgb *msg, uint8_t sapi)
 {
 	struct ue_conn_ctx *uectx = msg->dst;
 	struct osmo_scu_prim *prim;
@@ -405,13 +414,15 @@ static int sccp_sap_up(struct osmo_prim_hdr *oph, void *link)
 	return 0;
 }
 
-int sgsn_iu_init(void *ctx)
+int sgsn_iu_init(void *ctx, iu_recv_cb_t iu_recv_cb)
 {
 	struct osmo_sua_user *user;
 	int rc;
 
 	talloc_asn1_ctx = talloc_named_const(ctx, 1, "asn1");
 
+	global_iu_recv_cb = iu_recv_cb;
+
 	osmo_sua_set_log_area(DSUA);
 
 	user = osmo_sua_user_create(ctx, sccp_sap_up, ctx);
diff --git a/openbsc/src/gprs/sgsn_main.c b/openbsc/src/gprs/sgsn_main.c
index bb898fe7c..b0f758049 100644
--- a/openbsc/src/gprs/sgsn_main.c
+++ b/openbsc/src/gprs/sgsn_main.c
@@ -418,7 +418,7 @@ int main(int argc, char **argv)
 	}
 
 	asn_debug = 0;
-	sgsn_iu_init(tall_bsc_ctx);
+	sgsn_iu_init(tall_bsc_ctx, gsm0408_gprs_rcvmsg_iu);
 
 	if (daemonize) {
 		rc = osmo_daemonize();