[Freeswitch-users] How to set the IP of REGISTER message??

If my PC has two IP address, How to decide the IP which using to send REGISTER message?? For example, I have two IP , 172.30.30.XXX for External and 192.168.60.XXX for Internal, and now i want to add two gateway, one is 210.XXX.XXX.XXX and the other one is 192.168.60.30, How to change the IP that i want to use??