[SIPForum-discussion] Change of contact field when behind NAT

rahul sankanur rahul.sankanur at gmail.com
Fri Oct 11 09:31:00 UTC 2013

Hi all,

Mohit and Vijay ,thank you very much for the information....

I have a Belkin and a Dlink router..I have been seeing something very
strange in both...
I have two devices behind NAT and STUN is enabled in both ..Therefore in
their SDPs, the devices will be their respective mapped IP and ports..
But i see that the both the routers are NOT forwarding the media packets to
the other side..Both the end devices send to the  mapped IP and mapped
ports though...I get ICMP packets sometimes with destination port
unreachable (but media STUN keepalive is ON).

But when one device is inside NAT and other is outside , router is
forwarding properly...

So is there any other specific setting to be done in the routers or both
the routers' routing tables are flawed???

This problem arises only when 2 devices are in same NAT and media is
flowing through the mapped port of the routers....

Thanks and regards,
Rahul Sankanur
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