I see this in your output:
:callee's address filled in: 10.31.168.2:16004 (RTP)
Which means it received audio from that IP.
What I don't see is rtpproxy "prefilling" the addresses (caller and
callee) with the SDP data which is used to send audio until we know what
the real ip/port is. You should be seeing some info like:
pre-filling caller's address with....
pre-filling callee's address with....
If you don't see that, then are you sure that data is coming in the SDP
Invite? Without that info, rtpproxy has no way to relay your rtp before
receiving rtp from the other end.
Andres
http://www.telesip.net