asterisk: Enable IMS port advanced mode

This allows the SIPmsg_PT port module to be able to handle multiple
client sockets concurrently.
This allows workarounding for now a bug where Asterisk wrongly creates a
TCP conn 2 times and sending the REGISTER over the 2nd one, while TTCN3
operates only on the 1st accepted socket.

Change-Id: I287650a42c700c3959d0959620fb3f1e8e342c7d
diff --git a/asterisk/Asterisk_Tests.default b/asterisk/Asterisk_Tests.default
index 1de9def..503f767 100644
--- a/asterisk/Asterisk_Tests.default
+++ b/asterisk/Asterisk_Tests.default
@@ -12,6 +12,7 @@
 Asterisk_Tests_LOCAL_SIP_EMU.SIP.default_dest_port := "5060"
 Asterisk_Tests_LOCAL_SIP_EMU.SIP.default_dest_address := "127.0.0.1"
 # IMS Core:
+Asterisk_Tests_IMS_SIP_EMU.SIP.port_mode := "advanced"; # Allow concurrent client sockets
 Asterisk_Tests_IMS_SIP_EMU.SIP.default_sip_protocol := "TCP";
 Asterisk_Tests_IMS_SIP_EMU.SIP.listen_enabled := "enabled";
 Asterisk_Tests_IMS_SIP_EMU.SIP.local_sip_port := "5060"