You should use stun address resolution in order to find out whether you are behind NAT or not. There is a callback returning discovered NAT type in pjsua ( http://www.pjsip.org/pjsip/docs/html/structpjsua__callback.htm#a992011976963178f5b831d93ee058b7 ). Regards, Robert. -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.pjsip.org/pipermail/pjsip_lists.pjsip.org/attachments/20091124/8320d0b8/attachment.html>