Hi Joachim,
Thanks for your reply.
I've ran a trace and analysed it in Wireshark.
Zoiper initiates the call, telling us to send rtp traffic to 127.0.0.1 (not really allowed!). What we do in these situations is wait for rtp to be sent to us, and we then correct where we send the rtp to (we cannot send to 127.0.0.1).
We send 183 trying with correct sdp telling zoiper where to send traffic.
We send 200 ok with correct sdp telling zoiper where to send traffic.
Zoiper acks our OK.
No rtp traffic from Zoiper and no correct sdp from zoiper - so we have no information from zoiper where to send the traffic.
Do you have somewhere I can send you our trace, if it'd help?
Regards,
Carl