bsc: Permit MGCP messages from random ports on BSC side

Change-Id: Ie8896edc3f4310a78b584fd4ad017b77bda22afb
diff --git a/bsc/BSC_Tests.ttcn b/bsc/BSC_Tests.ttcn
index 7e5b675..9da5b65 100644
--- a/bsc/BSC_Tests.ttcn
+++ b/bsc/BSC_Tests.ttcn
@@ -191,7 +191,7 @@
 	};
 	var MGCP_conn_parameters mgcp_pars := {
 		callagent_ip := mp_bsc_ip,
-		callagent_udp_port := 2727,
+		callagent_udp_port := -1,
 		mgw_ip := mp_test_ip,
 		mgw_udp_port := 2427
 	};