Is it possible to run SER SIP server behind a NAT? If so, what type of configuration changes am i looking at? My current scenario is as follows. Internet <-----> Pix (12.x.x.x translates to 10.x.x.x) <----> SIP Server Requests to and from the internet have a static NAT translation rule in the PIX. Traffic flows from the outside global IP to an inside NAT'ed IP (non-routable) and vice versa. The SIP server's interface is configured with a non-routable IP addresss (10.x.x.x) for example. My problem is related to the message header and the ACK has a record route with the 10.x.x.x in it. Please help.