Sporadic Drop calls Looking for direction

[blair73]

I'm running into an issue where calls are getting dropped sporadically on inbound calls. The call flow.


PSTN Number 123-4567 is forwarded in the PSTN to 123-4000 as an example, that calls arrives via an AT&T IP Flex SIP trunk via a 4321 managed by AT&T. The 4321 hands off TDM PRI. Calls seem to arrive to the AVaya IP office, hit a hunt group that sends to a group of people on VPN based phones.


When the transfer the call this is when it seems to drop.. It doesn't happen all the time.. any ideas? Doesn't happen all the time.. From a System Monitor debug, it just shows call lost. Normal call clearing is 16.. Which tells me the other side dropped the call. Look at the AT&T router they say that we are disconnecting meaning the PRI is sending the disconnect.

[scottschilling]

What jumped out at me is that you think it's happening when they try to transfer. How about when they put a call on hold? Is there hold music, tones or silence when transferring/holding? Sometimes the equipment (AdTran, etc) that hands off a SIP connection to PRI can disconnect depending on the silence detection settings.

[wellington35]

Blair73 - Find out if the remote users hear the phone ring. The the hangup happens when the call gets answered by the VPN Phone, then it might be related to the "Direct Media Path" or Shuffling.
Try disabling it, and see if that improves it.

On IPFlex circuits the Service Provider can pull packet captures to and playback the RTP Media Stream to see where the disconnect happens. If it is coming form the Inbound or Outbound leg of the call.