On Oct 10, 2009, at 5:51 AM, Sourav Chakraborty wrote:
Hi List,
We are trying to establish a SIP session between two UAs which are behind NAT.The SIP proxy server is in the public domain.We are using SER(Sip Express Router) as SIP proxy and REGISTRAR and RTPProxy as the Media Proxy(rtpproxy is also running in the same public IP machine as SER).We are using DUM testClient (BasicCall.cxx) code as the UA code,on both the endpoints.
We have observed that when an INVITE is sent by the resiprocate UA(after proper REGISTRATION),it puts the local IP address in the "Contact" header.This is unlike that of a proper SIP client(Bria),which puts the NATted IP corresponding to the endpoint in the "Contact" header.
In order to get this behavior, you need to use STUN to discover the natted address, and set the Contact header to match. This isn't something DUM does for you.