Hi . When I send "INVATE" message to other client. I append "alt" attribute int sdp, "a=alt: 1 1.0 user xxxx 192.168.100.2 1000" It is means "a=alt:1 1.0 user xxx <local ip> <local port>" How to get the sdp attribute on the "on_call_state()", and How to change the taget media port in this function. Thanks in advance. Regards, charles -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.pjsip.org/pipermail/pjsip_lists.pjsip.org/attachments/20091102/17f2db94/attachment.html>