[c-nsp] voice call drop on as5400

[a0kunev]

Hello

I would like to share the problem we recently got on our network. We have DS3 coming to as5400, that converting PSTN calls to VOIP. We're handling only incoming calls, so the dial-pear config is simple, one voice and one voip provider. Recently we've started receiving complains from our customers on dead air and drops during their conferences. The issues looked like this - person dialed to the DID and nobody answered during 10-120 secounds, then the call terminated by timeout. 

recently we're able to reproduce this, with debug 'call-mgmnt' it's dumping the following on console:
Aug 19 11:08:06.478: msg_to_calls_mgmt: msg type CPM_VOICE_CALL_MOD_REJ received
Aug 19 11:08:06.478: msg_to_calls_mgmt: msg type CPM_VOICE_CALL_MOD_REJ received
Aug 19 11:08:06.478: msg_to_calls_mgmt: msg type CPM_VOICE_CALL_MOD_REJ received
Aug 19 11:08:06.478: msg_to_calls_mgmt: msg type CPM_VOICE_CALL_MOD_REJ received
Aug 19 11:08:06.482: from Trunk(7): Bad CID 2A3(2A7) s3/p85 u1/c7 event 3
Aug 19 11:08:06.482: from Trunk(7): Bad CID 2A4(2AB) s3/p86 u1/c6 event 3
Aug 19 11:08:06.486: from Trunk(7): Bad CID 2A5(2A8) s3/p87 u1/c8 event 3
Aug 19 11:08:06.486: from Trunk(7): Bad CID 2A6(2AB) s3/p88 u1/c6 event 3

I've checked with tcpdump cisco do not send anything to IP bridge to establish the call at that time. Telco says they see a lot of rejected calls from our side, but there is nothing on our end(I have not seen yet)

as5400 were recently updated to 12.4(9)T4.

Please advise on how to debug this problem.
regards, Andrei