Calls drop out after 15 seconds using PSTN
 

I am running PBXinaFlash, and have everything working fine with normal inbound calls. However, when I receive a call placed through a SipBroker PSTN number, the call completes, but then drops after about 10-15 seconds.

In the Asterisk log, I get the following lines:

WARNING[10010] chan_sip.c: Maximum retries exceeded on transmission 57d90bf2082b8c3e777ff0ea5bf0d010@204.11.194.10 for seqno 102 (Critical Response)

WARNING[10010] chan_sip.c: Hanging up call 57d90bf2082b8c3e777ff0ea5bf0d010@204.11.194.10 - no reply to our critical packet.

Does anyone have a solution for this? I have set port forwarding for all the common SIP ports, but no improvement. Thanks