I realize this last email has no useful information, so let me elaborate. I have a Kamailio server on AWS with an internal IP of 10.20.30.40 and it has an external elastic IP of 55.66.77.88. When a SIP client subscribes it sends the initial subscription to user@realm (where realm resolves to 55.66.77.88) , then it gets a notify with a new address <sip:10.20.30.40:5060;transport=udp> . The client attempts to refresh the subscription, but we are now sending the subscribes to this new contact which will time out. 300 seconds later, we subscribe again to user@realm and contacts show up. Other stuff like rtp, inbound/outbound calling all work properly. Pramod Venugopal pramod(a)dvnull.org From: sr-users on behalf of Pramod Venugopal Reply-To: "Kamailio (SER) - Users Mailing List" Date: Thursday, August 20, 2015 at 10:38 PM To: "Kamailio (SER) - Users Mailing List" Subject: [SR-Users] Presence and NAT Hello everyone, I have a Kamailio 4.2 system on Amazon AWS. When subscribing to presence the contact is sent out with the internal IP rather than the external public IP. The subscribes are being sent to it with the external hostname ( which resolves to the external IP ). Where would I be able to change the IP sent in the Contact header ? Pramod Venugopal pramod(a)perseus-tech.com _______________________________________________ SIP Express Router (SER) and Kamailio (OpenSER) - sr-users mailing list sr-users(a)lists.sip-router.org http://lists.sip-router.org/cgi-bin/mailman/listinfo/sr-users