Sorry for the long delay, but here's your answer: It's going to go to the address in the un-altered VIA header, unless RPORT gets sent it the VIA. If you have agressive_nat_detection turned on, and the client puts RPORT in the via, it will work fine. If you have a broken device that won't do it, then set the variable "NDLB-connectile-dysfunction=true" in the users directory enter (XML) or other, what ever you are using. That will cause the contact to be re-written to the transport address from where it came (both ip address and port) and the response will also be sent there. --Dave _____ From: BELint Inc [mailto:belintinc@gmail.com] To: freeswitch-users@lists.freeswitch.org Sent: Thu, 07 Jun 2012 10:56:07 -0700 Subject: Re: [Freeswitch-users] Freeswitch is responding to contact's port when client behind NAT Does any one know its solutions, Guys please help, its urgent. I am even unable to register my phones :-( Regards, On Thu, Jun 7, 2012 at 9:20 AM, BELint Inc <belintinc@gmail.com> wrote: Hi All, We`ve been using freeswitch since very long, It was good all over but it got stuck to a simple yet complex situation. We have Yealink T28P series phones behind NAT and freeswitch is unable to get them register. In the scenario freeswitch is at public IP. The reason we think is that freeswitch is using sip port in contact header to respond to. Is there anyway we can avoid this or force it to always send the response to destination IP instead of contact or via header ports because clients are behind NAT and response can only reach them if it respond to destination IP & PORT. Please revert if someone know how to solve this problem. It is very urgent. Regards BELint