diff --git a/mgw/MGCP_Test.ttcn b/mgw/MGCP_Test.ttcn
index e8e3ae3..1a21974 100644
--- a/mgw/MGCP_Test.ttcn
+++ b/mgw/MGCP_Test.ttcn
@@ -1990,7 +1990,9 @@
 
 	/* create two local RTP emulations and pass data in both directions */
 	function f_tc_two_crcx_mdcx_and_rtp(charstring local_ip_a, charstring remote_ip_a,
-					    charstring local_ip_b, charstring remote_ip_b) runs on dummy_CT {
+					    charstring local_ip_b, charstring remote_ip_b,
+					    uint7_t payload_type := 3,
+					    charstring codec_name := "GSM/8000/1") runs on dummy_CT {
 		var RtpFlowData flow[2];
 		var RtpemStats stats[2];
 		var MgcpResponse resp;
@@ -2002,13 +2004,13 @@
 		f_init(ep);
 
 		/* Create the first connection in receive only mode */
-		flow[0] := valueof(t_RtpFlow(local_ip_a, remote_ip_a, 3, "GSM/8000/1"));
+		flow[0] := valueof(t_RtpFlow(local_ip_a, remote_ip_a, payload_type, codec_name));
 		flow[0].em.portnr := 10000;
 		f_flow_create(RTPEM[0], ep, call_id, "recvonly", flow[0], true);
 
 		/* Create the second connection. This connection will be also
 		 * in receive only mode */
-		flow[1] := valueof(t_RtpFlow(local_ip_b, remote_ip_b, 3, "GSM/8000/1"));
+		flow[1] := valueof(t_RtpFlow(local_ip_b, remote_ip_b, payload_type, codec_name));
 		flow[1].em.portnr := 20000;
 		f_flow_create(RTPEM[1], ep, call_id, "recvonly", flow[1], true);