I want to cofig ser as a outbound server to resolve all nat problem. The follow picture is the system architecture.
 
uac--nat-->outboud1(ser1+nathelper+rtpproxy)------------->ser(main)
uac--nat-->outboud2(ser2+nathelper+rtpproxy)-------------|
uac--nat-->outboud3(ser3+nathelper+rtpproxy)-------------|
 
Can someone know if ser can rewrite the uac's contact as itself ip address and
forward to main ser? Nathelper can rewrite sdp ip/port to it own ip/port. But it
only rewrite contac with nat's ip and port.