diff --git a/bsc-nat/BSCNAT_Tests.ttcn b/bsc-nat/BSCNAT_Tests.ttcn
index fda065af5..47d894b57 100644
--- a/bsc-nat/BSCNAT_Tests.ttcn
+++ b/bsc-nat/BSCNAT_Tests.ttcn
@@ -16,6 +16,7 @@ import from Osmocom_Types all;
 import from IPL4asp_Types all;
 
 import from IPA_Emulation all;
+import from RAN_Emulation all;
 
 import from MTP3asp_Types all;
 
@@ -24,6 +25,7 @@ import from SCCPasp_Types all;
 import from SCCP_Emulation all;
 
 import from MSC_Simulation all;
+import from MSC_ConnectionHandler all;
 import from BSC_MS_Simulation all;
 import from BSC_MS_ConnectionHandler all;
 
@@ -136,7 +138,7 @@ function f_init_vty(charstring id := "foo") runs on test_CT {
 	f_vty_transceive(BSCNATVTY, "enable");
 }
 
-function f_init(void_fn_bsc_ms fn_bsc_ms, boolean use_osmux) runs on test_CT {
+function f_init(void_fn_bsc_ms fn_bsc_ms, BssmapCreateCallback cb_msc, boolean use_osmux) runs on test_CT {
 	var integer i;
 	var charstring id;
 
@@ -147,7 +149,9 @@ function f_init(void_fn_bsc_ms fn_bsc_ms, boolean use_osmux) runs on test_CT {
 		f_init_MscState(msc[i], mp_msc_pc +i, mp_bsc_pc, mp_msc_ssn, mp_bsc_ssn);
 		id := "MSC" & int2str(i);
 		msc[i].MSC := MSC_CT.create(id);
-		msc[i].MSC.start(MSC_Simulation.main(mp_msc_ip, mp_msc_port + i, msc[i].sccp_pars, msc[i].sccp_addr_own, id));
+		msc[i].MSC.start(MSC_Simulation.main(mp_msc_ip, mp_msc_port + i,
+						     msc[i].sccp_pars, msc[i].sccp_addr_own,
+						     cb_msc, id));
 	}
 
 	/* Wait for bsc_nat to attach to MSC. Before that all BSC connections will be dropped */
@@ -186,7 +190,9 @@ function f_wait_finish(timer T) runs on test_CT {
 function f_TC_recv_dump(boolean use_osmux := false) runs on test_CT {
 	timer T := 30.0;
 
-	f_init(refers(bsc_ms_establish_fully), use_osmux);
+	f_init(refers(bsc_ms_establish_fully),
+	       refers(CreateCallback_establish_fully),
+	       use_osmux);
 
 	f_wait_finish(T);
 }
diff --git a/bsc-nat/MSC_ConnectionHandler.ttcn b/bsc-nat/MSC_ConnectionHandler.ttcn
index c8cb00590..e4d381669 100644
--- a/bsc-nat/MSC_ConnectionHandler.ttcn
+++ b/bsc-nat/MSC_ConnectionHandler.ttcn
@@ -21,6 +21,8 @@ import from MGCP_Types all;
 import from MGCP_Templates all;
 import from SDP_Types all;
 
+type function void_fn_msc(charstring id) runs on MSC_ConnHdlr;
+
 /* this component represents a single subscriber connection at the MSC.
  * There is a 1:1 mapping between SCCP connections and RAN_ConnHdlr components.
  * We inherit all component variables, ports, functions, ... from RAN_ConnHdlr */
@@ -32,24 +34,38 @@ type component MSC_ConnHdlr extends RAN_ConnHdlr {
 	var MgcpEndpoint g_ep_name;
 	var MgcpCallId g_call_id;
 	var MgcpConnectionId g_mgcp_conn_id;
+	var MSC_TestHdlrParams g_pars;
 }
 
-/* Callback function from general BSSMAP_Emulation whenever a new incoming
- * SCCP connection arrivces. Must create + start a new component */
-private function CreateCallback(BSSAP_N_CONNECT_ind conn_ind, charstring id)
-runs on RAN_Emulation_CT return RAN_ConnHdlr {
-	var MSC_ConnHdlr vc_conn;
-	/* Create a new RAN_ConnHdlr component */
-	vc_conn := MSC_ConnHdlr.create(g_ran_id & "-Conn-" & int2str(conn_ind.connectionId));
-	/* connect it to the port */
+type record MSC_TestHdlrParams {
+	integer connection_id,
+	integer e1_timeslot
+};
+
+/* helper function to create and connect a MSC_ConnHdlr component */
+private function f_connect_handler(inout MSC_ConnHdlr vc_conn) runs on RAN_Emulation_CT {
+	/* connect client BSSAP port to BSSAP dispatcher */
 	connect(vc_conn:BSSAP, self:CLIENT);
-	/* start it */
-	vc_conn.start(MSC_ConnectionHandler.main(conn_ind.connectionId, g_next_e1_ts));
-	/* increment next E1 timeslot */
-	g_next_e1_ts := g_next_e1_ts + 1;
+}
+
+private function f_msc_start_handler(void_fn_msc fn, charstring id, template (omit) MSC_TestHdlrParams pars := omit)
+runs on RAN_Emulation_CT return MSC_ConnHdlr {
+	var MSC_ConnHdlr vc_conn;
+	vc_conn := MSC_ConnHdlr.create(id);
+	f_connect_handler(vc_conn);
+	vc_conn.start(f_handler_init(fn, id, pars));
 	return vc_conn;
 }
 
+/* first function inside ConnHdlr component; sets g_pars + starts function */
+private function f_handler_init(void_fn_msc fn, charstring id, template (omit) MSC_TestHdlrParams pars := omit)
+runs on MSC_ConnHdlr {
+	if (isvalue(pars)) {
+		g_pars := valueof(pars);
+	}
+	fn.apply(id);
+}
+
 /* Callback function from general BSSMAP_Emulation whenever a connectionless
  * BSSMAP message arrives.  Can retunr a PDU_BSSAP that should be sent in return */
 private function UnitdataCallback(PDU_BSSAP bssap)
@@ -63,8 +79,25 @@ runs on RAN_Emulation_CT return template PDU_BSSAP {
 	return resp;
 }
 
+/* Callback function from general BSSMAP_Emulation whenever a new incoming
+ * SCCP connection arrivces. Must create + start a new component */
+private function CreateCallback_generic(void_fn_msc fn, BSSAP_N_CONNECT_ind conn_ind, charstring id)
+runs on RAN_Emulation_CT return RAN_ConnHdlr {
+	var MSC_ConnHdlr vc_conn;
+	var MSC_TestHdlrParams pars;
+	pars.connection_id := conn_ind.connectionId;
+	pars.e1_timeslot := g_next_e1_ts;
+
+	/* Create a new RAN_ConnHdlr component */
+	vc_conn := f_msc_start_handler(fn, g_ran_id & "-Conn-" & int2str(conn_ind.connectionId), pars);
+
+	/* increment next E1 timeslot */
+	g_next_e1_ts := g_next_e1_ts + 1;
+	return vc_conn;
+}
+
 const RanOps MSC_RanOps := {
-	create_cb := refers(CreateCallback),
+	create_cb := omit,
 	unitdata_cb := refers(UnitdataCallback),
 	decode_dtap := false,
 	role_ms := false,
@@ -84,14 +117,20 @@ type enumerated MSC_State {
 	MSC_STATE_WAIT_DLCX_ACK
 }
 
+/* Callback function from general BSSMAP_Emulation whenever a new incoming
+ * SCCP connection arrivces. Must create + start a new component */
+function CreateCallback_establish_fully(BSSAP_N_CONNECT_ind conn_ind, charstring id)
+runs on RAN_Emulation_CT return RAN_ConnHdlr {
+	return CreateCallback_generic(refers(f_msc_establish_fully), conn_ind, id);
+}
 /* main function processing various incoming events */
-function main(integer connection_id, integer e1_timeslot) runs on MSC_ConnHdlr {
+function f_msc_establish_fully(charstring id) runs on MSC_ConnHdlr {
 	var MgcpResponse mgcp_rsp;
 	timer T := 5.0;
 
-	g_sccp_conn_id := connection_id;
+	g_sccp_conn_id := g_pars.connection_id;
 	g_call_id := f_mgcp_alloc_call_id();
-	g_ep_name := hex2str(int2hex(e1_timeslot, 1)) & "@mgw";
+	g_ep_name := hex2str(int2hex(g_pars.e1_timeslot, 1)) & "@mgw";
 
 	/* we just accepted an incoming SCCP connection, start guard timer */
 	T.start;
@@ -103,7 +142,7 @@ function main(integer connection_id, integer e1_timeslot) runs on MSC_ConnHdlr {
 		[g_state == MSC_STATE_NONE] BSSAP.receive(tr_BSSMAP_ComplL3) -> value bssap {
 			/* respond with ASSIGNMENT CMD  */
 			g_state := MSC_STATE_WAIT_ASS_COMPL;
-			BSSAP.send(ts_BSSMAP_AssignmentReq(ts_BSSMAP_IE_CIC(0, e1_timeslot)));
+			BSSAP.send(ts_BSSMAP_AssignmentReq(ts_BSSMAP_IE_CIC(0, g_pars.e1_timeslot)));
 			}
 		[g_state == MSC_STATE_WAIT_ASS_COMPL] BSSAP.receive(tr_BSSMAP_AssignmentComplete(?,*)) {
 			/* FIXME: Send MGCP CRCX */
diff --git a/bsc-nat/MSC_Simulation.ttcn b/bsc-nat/MSC_Simulation.ttcn
index bc47f89f0..14229cc66 100755
--- a/bsc-nat/MSC_Simulation.ttcn
+++ b/bsc-nat/MSC_Simulation.ttcn
@@ -38,7 +38,8 @@ modulepar {
 
 function main(charstring local_ip, PortNumber local_port,
 	      MSC_SCCP_MTP3_parameters sccp_pars,
-	      SCCP_PAR_Address sccp_addr_own, charstring id) runs on MSC_CT
+	      SCCP_PAR_Address sccp_addr_own,
+	      BssmapCreateCallback cb, charstring id) runs on MSC_CT
 {
 	/* create components */
 	vc_IPA := IPA_Emulation_CT.create(id & "-IPA");
@@ -64,7 +65,10 @@ function main(charstring local_ip, PortNumber local_port,
 
 	vc_IPA.start(IPA_Emulation.main_server(local_ip, local_port));
 	vc_SCCP.start(SCCPStart(sccp_pars));
-	vc_BSSMAP.start(RAN_Emulation.main(MSC_ConnectionHandler.MSC_RanOps, id & "-BSSMAP"));
+
+	var RanOps ranops := MSC_ConnectionHandler.MSC_RanOps;
+	ranops.create_cb := cb;
+	vc_BSSMAP.start(RAN_Emulation.main(ranops, id & "-BSSMAP"));
 
 	/* wait until termination of respective components */
 	vc_IPA.done;