Please do not retransmit the same mail to multiple mailing lists. The sr-dev is for development of the source code of Kamailio and this question is related to usage of Kamailio.Hi, I read in http://kamailio.org/docs/modules/1.4.x/nathelper.html that Kamailio might rewrite ip address in o= in SDP to facilitate NAT traversal.It may decide to use to original IP or use IP of RTP server. What factors affect its decision ?