NethVoice: TIM Trunk Compatibility and Dialplan Adjustments #7321

🔧 Configuration Requirements for TIM Trunk

To ensure full compatibility with the TIM SIP trunk, the following changes are required on both the phone configuration and the Asterisk dialplan:

📞 Phone Configuration

1. Codec Prioritization (G729):

   • Provisioned phones must prioritize the G729 codec to ensure it is used as the primary codec for outgoing calls.
   • Action Required: Tancredi must provide a phone template that sets G729 as the first codec in priority order.
   • NethVoice Configuration: The G729 codec must be enabled in FreePBX under the codec settings, ensuring consistency across the system and propagation to the TIM trunk.

📜 FreePBX Dialplan Modifications

1. Incorrect SIP Response for Unregistered Extensions:

   • Previously, when an incoming call was routed to an unregistered extension, the system responded with a 6XX SIP error, which is formally incorrect.
   • Fix: The dialplan in macro-exten-vm was updated to return cause 20 (Subscriber absent) instead, as shown below:

   exten => _s-!,1,GotoIf($["${IVR_RETVM}"="RETURN" & "${IVR_CONTEXT}"!=""]?exit,1)
   exten => _s-!,n,Playtones(congestion)
   exten => _s-!,n,HangUp(20)
   
   ; Previous (incorrect) implementation:
   ; exten => _s-!,1,GotoIf($["${IVR_RETVM}"="RETURN" & "${IVR_CONTEXT}"!=""]?exit,1)
   ; exten => _s-!,n,Playtones(congestion)
   ; exten => _s-!,n,Congestion(10)
   

2. Auto-answer Interference with Call Forwarding:

   • When handling direct DID calls that require diversion, enabling auto-answer on the inbound route was necessary to preserve audio.
   • However, this behavior caused internal calls to be answered prematurely, before the actual recipient responded.
   • Fix: In macro-dial-one, insert an Answer() directive only when the call forward (CF) logic is active, ensuring that auto-answer is applied only in appropriate call diversion scenarios.

After further tests, it is necessary to also add ringing() as in the figure: