We have a service from SIP provider which sends some DID numbers to my public IP address. Officeserv 7400 is setup behind my firewall. VoIp is on same public IP and works fine.
We did all the SIP config on the system and I am pretty positive everything is fine there as well.
Now when i dial the SIP number, it rings and then gets disconnected. By default it is forwarded to operator.
I did some packet trace and found that call signal is coming to my firewall gets forwarded to my MCP IP just fine. However I dont see anything coming back from my MCP on the trace.
Voice will be later part but right now even signalling is not working. Call doesnt ring on operator phone as it should.

Any thoughts?