Depending on the requirements, it may not be sufficient to transmit "inband" DTMF tones if a SIP receiver cannot recognize these. In this case, it is possible to configure an alternative method of DTMF transmission for All-IP connections.
- SNMP ID:
- 2.33.4.1.1.27
- Console path:
- Setup > Voice-Call-Manager > Lines > SIP-Provider > Line
- Possible values:
- Inband
- The tones are transmitted as DTMF tones (G.711) in the RTP (voice) stream.
- SIP-INFO
- The DTMF tones are transmitted "out-of-band" as a SIP-info message with the parameters Signal and Duration (as per RFC 2976). There is no parallel transmission of G.711 tones.
- RTP-Event
- The DTMF tones are transmitted as specially marked events within the RTP stream (as per RFC 4733). There is no parallel transmission of G.711 tones. If the call-initialization SDP message does not include telephone-event signaling, negotiations fallback to inband transfer as per G.711.
- RTP-Event/SIP-Info
- The DTMF tones are transmitted as specially marked events within the RTP stream (as per RFC 4733). There is no parallel transmission of G.711 tones. If the call-initialization SDP message does not include telephone-event signaling, negotiations fallback to transfer as per SIP-Info message.
- Default:
- RTP-Event
