I have following setup
Outside Caller --- SIP TRUNK ---- CALL MANAGER ---- Phone A RNA VOICE MAIL ---- (SCCP Ports) ---- CALL MANAGER ------- SIP or SCCP Phone B
1. Inbound call on SIP Trunk to Phone A
2. Phone A RNA trigger and calls forwarded to VM
3. Outside User hear a Personal Greeting and press "0" to transfer to operator phone B
4. I see call Ringing on Phone B but ouside user do not hear ringback tone
5. Outside user hear disconnect tone but still call is ringing on Phone B and no audio if answer
VM system is not Cisco and it has SCCP integration with UCM.
Call from SIP trunk is g729 and I do have HW xcoder and MTP in MRGL.