Multiplexing of SIP and RTP On One Socket

Contact: Jan Janak

For some specialized setups and testing it would be useful if sip-router supported multiplexing of several protocols on one socket, in particular on sockets that are used to receive SIP traffic.

The primary motivation for such an extension is the possibility to multiplex SIP and RTP on one port, but it could be useful for other protocols too. Namely STUN, the ability to multiplex SIP and STUN on the same socket is crucial for properly working NAT traversal in SIP user agents.

We already did some work on STUN support in SER a long time and we were able to run a STUN server within SER, on port 5060, multiplexed with SIP.

The goal of this work is to revive this code in the sip-router project. We would also like to take it a bit further and add the possibility to multiplex more protocols than just STUN and SIP (namely RTP).

It would be also nice if either the SIP socket itself or data received on that socket could be shared with another application running on the same host.