The setup our customer has is as follows: They have a CUCM 5.0 as their phone system with a UNITY for voicemail. Our SIP-based system is connected to the CUCM via a SIP trunk. VAD is disabled on the CUCM and when we have a call between our system and CUCM all is fine, no VAD kick in even if no voice activity. The issue is when the phone on the CUCM side does not answer and the call is fowarded on to the UNITY voicemail. The voice prompt from UNITY is played then the beep, but after we receive a RTP packet with comfort noise payload then the RTP traffic from UNITY stops. Our application does not support an interuption of RTP traffic and times out.
Is there any way to configure the UNITY to transmit silence RTP packets after the prompt is played?