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telephone-event and other digit paths
telephone-event is RFC 4733, a dynamic payload. Events 0 through 15 are DTMF. INFO and KPML are different tools.
Learn in 5 minutes
- Negotiate telephone-event in SDP by encoding name
- Limit DTMF events to 0 through 15
- Keep SIP INFO and KPML separate from RFC 4733
Visual
Only telephone-event is RTP. The others are signaling, and one of them is not an IETF body.
Worked example
Negotiate telephone-event The offer uses payload 101 and the answer uses payload 106. Both rtpmap lines say telephone-event/8000 and fmtp lists 0-15.
- Press Negotiate.
- Find telephone-event on each side.
- Compare the payload type numbers and the fmtp range.
Fault
Key presses never reach the far media path. The trace shows INFO with a vendor body and the SDP has no telephone-event line.
RFC 6086 defines INFO. The body type application/dtmf-relay is a vendor convention, not an IETF standard, and it is not the telephone-event codec.
Quiz
Ecosystem
Glossary, sister systems, and the integration seam for this room.
CRM Screen pop uses data the contact center already has: ANI, DNIS, case id. Those values may arrive in SIP headers or in a CTI event after the call is up. The CRM is not a SIP element.