Hello,
I have SER setup to only use the rtpproxy if the client is behind a symmetric NAT. This is accomplished by using STUN since STUN will not modify the contact headers if it detects a symmetric NAT. So SER see's the local address in the contact header and only forces rtpproxy for those types of call. When users are behind the same NAT then ser detects this using AVP's and force_rtpproxy is not used for the call. This only works when STUN is not enabled. Since when STUN succeeds the orignal local address of the phone is changed to the public address in the sip message. So when two STUN enabled clients try to call each other from behind the same nat the call fails. The call fails because the NAT does not support harpin of media as most don't. The only way this call would work is if the contacts could be changed back to use their local addresses pre-STUN. How can SER be instructed to use the local address for calls behind the same NAT when STUN is enabled? One way I can think of doing this is to change nathelper to extract the original IP from the VIA header and rewrite the SDP. In the SIP trace i see only IP's in contact headers and SDP are changed when STUN succeeds. Is there a simpler way to accomplish this?
Thanks, Sumeet
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