Hi, I have a similar issue,
It is not possible to debug this issue without full SIP trace!
ngrep -Wbyline -t -d any port 5060
I find it unpleasant to read such a trace. Please really use ngrep to get a nice formated SIP trace, or supply the pcap file.
Ok, here it goes again.
Pay attention to the "200: OK" response from the PSTN-GW. I think its Contact header should be read by the Cisco GW (calling party), and then send its ACK-request with R-URI based on that Contact. But it doesn't happen. Then here i think this is the failure. (rfc3261, section 12.1.1 and 12.2.1.2). May i am wrong..
What do you think? I'd appreciate your comments.
You are right. Caller behaves wrong, it should send ACK with RURI=ContactOf200Ok.
Maybe this is a buggy NAT traversal feature of Caller (Cisco?) which can be turned off.
If you can't fix it at Caller-side, you can make some workarounds at the proxy (if it is a fixed routing to the other gateway)
I think being a cisco device, there isn't too much to touch/modify. Just to start thinking about a workaround. Which kind of modification, source code or ser.cfg config? Maybe accepting and relaying all ACKs sent by this gw; simple, but insecure, not sure.
Thank you Klaus, Caio