Hi All,

I have deployed a Kamailio proxy server (as IMS pCSCF) in Amazon EC2. UA registration over TCP and presence flow (PUBLISH/NOTIFY) are all fine. But MESSAGE from one UA to another is UA over TCP is always not successful. I captured the sip flow from the server, and found that at the final hop from Proxy to terminating UA, the Kamailio server send the MESSAGE over udp, regardless of the fact that UAs were registered over TCP.

What is the problem maybe? Attached is the cfg file.

Thanks.

Thierry Luo