CME sends a BYE without receiving one first

[MVK]

I ran into a strange problem this weekend with a 2951. We have a CUCM, the 2951 is used as an edge device to convert from IPv6 to IPv4 and let the CUCM connect to a remote phone system. So there is a dial-peer to the CUCM and the remote system. The problem we ran into was in inbound calls. They seem to complete, the 2951 passes out the 200 OK to the remote system, we get an ACK but. But then the 2951 spontaneously sends out a BYE without receiving anything from the CUCM to tell it to end the call. Has anyone seen something like this?

[Dennis Mink]

you would need to run debugs on the 2951, as this is not liking something as it is sending the BYE, debug like voice ccapi inout/debug voip dialpeer. state calling and called number and 2951 config

[Mohammed al Baqari]

Along with Dennis request, attach debug ccsip message. The BYE message will
have cause code which can hint

[MVK]

Thanks for the suggestions, they got me pointed in the right direction. It turned out to be a codec mismatch. After fixing that calls are working fine.