We have a 0.9.X setup that works fine and have set up the system to listen on multiple ports with the following listen=udp:xx.xx.xx.xx:5060 udp:xx.xx.xx.xx:5062 The problem is that when setting the "record route" we want to use the port that the message came in on rather than simply a static value... record_route_preset("xx.xx.xx.xx:5060;nat=yes"); Something like if (receive port == 5060) { record_route_preset("xx.xx.xx.xx:5060;nat=yes"); } else if (receive port ==5062) { record_route_preset("xx.xx.xx.xx:5062;nat=yes"); }; What can we check in ser.cfg? Thanks in advance.