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FXO to FXS connection, getting split second of secondary dial tone then drops

IP Phone -> CUCM -> H323 gateway -> outbound dial peer that forwards no digits -> FXO port -> FXS port (DN = 9997) -> dial-peer with no direct inward dial command


My expectation is that when I dial  9997 that my call would be sent out the FXO port, the FXS would go off hook, the port is matched for the incoming dial peer and since I am not sending any digits outbound and I do not have DID on the inbound dial peer, that I would get secondary dial tone.


I do get a split second of secondary dial tone and then the call drops


The FXO is in a 2951 and the FXS is in a 2811


Both FXO and FXS are set to loopstart


What is interesting is that if I set the FXS voice port to do connection plar, the call rings once to the target phone and then drops.


However, if I configure the outbound dial peer to send 4 digits to the FXS port AND maintain the PLAR command, the call completes fine to the target phone and I am able to talk back and forth without the call hanging up.


I suspect timers – but I am unsure.  I added timeout initial 5, timeouts interdigit 5 with no changes.


Any ideas?



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