diff --git a/msc/BSC_ConnectionHandler.ttcn b/msc/BSC_ConnectionHandler.ttcn
index fb2d888..5b0a125 100644
--- a/msc/BSC_ConnectionHandler.ttcn
+++ b/msc/BSC_ConnectionHandler.ttcn
@@ -1044,12 +1044,19 @@
 		}
 
 	//[g_pars.ran_is_geran] BSSAP.receive(tr_BSSMAP_AssignmentReq(omit, tla_ass)) -> value bssap {
-	[] BSSAP.receive(tr_BSSMAP_AssignmentReq(omit, tla_ass)) -> value bssap {
+	[] BSSAP.receive(tr_BSSMAP_AssignmentReq(omit)) -> value bssap {
 		log("f_mo_call_establish 4: rx Assignment Request");
 		var BSSMAP_IE_AoIP_TransportLayerAddress tla;
 		var BSSMAP_IE_SpeechCodec codec;
 		var BSSMAP_IE_Osmo_OsmuxCID osmuxCID;
 
+		if (tla_ass != bssap.pdu.bssmap.assignmentRequest.aoIPTransportLayer) {
+			log("Expected:", tla_ass);
+			log("Got:", bssap.pdu.bssmap.assignmentRequest.aoIPTransportLayer);
+			setverdict(fail, "MSC sent Assignment Request with unexpected AoIP Transport Layer IE");
+			mtc.stop;
+		}
+
 		tla := valueof(ts_BSSMAP_IE_AoIP_TLA4(f_inet_addr(cpars.bss_rtp_ip), cpars.bss_rtp_port));
 		codec := valueof(ts_BSSMAP_IE_SpeechCodec({ts_CodecFR}));
 		if (cpars.use_osmux) {