Symptom

No way audio for externally transferred calls with below call flow. Call flow:Mobile/Phone >> Provider >> SIP >> CUBE >> SIP >> CUCM >> CTI >> IVR >> CUCM >> SIP >> CUBE >> SIP >> Provider >> Agent Phone (It is not just restricted to the call flow mentioned. Trigger of the issue is mentioned under condition. Any call flow which can trigger it will hit the issue) IOS: 15.5(3)M5 Observations based on debugs and captures: 1. Analyzed couple of problematic call's cube debugs and packet captures. Signaling completed good for both problematic calls. Both problematic calls have exact call flow mentioned above. Provider has enabled in-dialogue options ping. 2. On completion of transfer media is hair pinned within cube. I see issues once media is hair pinned on cube. 3. On completion of transfer cube send g711alaw towards provider in first call leg. But from provider receives g711ulaw. As per signaling end to end codec should be g711ulaw. 4. Also notice on completion of transfer cube is not sending rtp towards providers second leg (IVR transfer call to provider). 5. Issue is notice only for calls termination first and second call leg on same cube. No issues noticed if calls comes in through isdn gateway and ivr transfer the call to provider over the problematic cube. 6. Issue is noticed when cube hair pin media.

Conditions

Bad calls receive in-dialog options ping after the transaction is completed and CUBE receives ACK. For good calls, OPTIONS is received before ACK. When OPTIONS ping is received after ACK, preferred codec is taking g711alaw from static codec, which is wrong. While the codec is set to g711alaw, it is not programmed till the next signaling exchange of transfer is completed - due to which the problem is seen post transfer. But it does not looks to be restricted to transfer . It is just that cube is programmed to change codec (change codec due to in-dialog options ping receive post ack) in media next signal exchange.

Workaround

++ Disable options ping.

Further Problem Description