Hi! I'm trying to make a point-to-point voice (not video) call from linphone on one machine (call this machineA) to linphone on machineB. I don't have a sip server and don't want to require one for this. I can happily, on machineA, call address@hidden and this works perfectly for testing. However... machineB is actually only available via SSH. I can ssh into machineB from machineA, and I can forward ports both forward and backwards along this SSH connection. Which ports do I need to forward, and in which directions, to enable a SIP voice call?
For example, I can set up a SIP port forward by doing, on machineA:
ssh -L 9998:localhost:5060 machineB
which forwards port 9998 on machineA to port 5060 on machineB. I can then make a sip call, on machineA, to sip:address@hidden:5060 and that works fine and the SIP call connects! Excellent. (I also need to turn on tcp, not udp, of course.)
However... there's only audio in one direction, and I get a million errors from RTP saying that it can't connect. I think I probably have to forward another port for the RTP connection, and possibly a port in both directions? But I also need linphone on machineA to know where this forwarded port is, so it can connect to _that_ rather than to machineB:rtpport. So, perhaps there's a list of the things that need to happen here, or some of you have some guidance on the best approach here? (I know one approach would be "run a SIP server", but that's not available for this.)