RTP Payload for DTMF Digits, Telephony Tones, and Telephony Signals
RFC 4733, “RTP Payload for DTMF Digits, Telephony Tones, and Telephony Signals”, is a Proposed Standard document published in December 2006 by H. Schulzrinne, T. Taylor. It obsoletes RFC 2833. It has since been updated by RFC 4734, RFC 5244. The canonical text is published by the RFC Editor.
Abstract
This memo describes how to carry dual-tone multifrequency (DTMF) signalling, other tone signals, and telephony events in RTP packets. It obsoletes RFC 2833.
This memo captures and expands upon the basic framework defined in RFC 2833, but retains only the most basic event codes. It sets up an IANA registry to which other event code assignments may be added. Companion documents add event codes to this registry relating to modem, fax, text telephony, and channel-associated signalling events. The remainder of the event codes defined in RFC 2833 are conditionally reserved in case other documents revive their use.
This document provides a number of clarifications to the original document. However, it specifically differs from RFC 2833 by removing the requirement that all compliant implementations support the DTMF events. Instead, compliant implementations taking part in out-of-band negotiations of media stream content indicate what events they support. This memo adds three new procedures to the RFC 2833 framework: subdivision of long events into segments, reporting of multiple events in a single packet, and the concept and reporting of state events. [STANDARDS-TRACK]
What “Proposed Standard” means
An entry-level standards-track specification: stable, peer-reviewed and a solid basis for implementation, though it may still evolve before becoming an Internet Standard.
The canonical text of RFC 4733 is hosted at rfc-editor.org. Available in TXT,HTML.
- RFC 4732 Internet Denial-of-Service Considerations
- RFC 4734 Definition of Events for Modem, Fax, and Text Telephony Signals
- RFC 4731 IMAP4 Extension to SEARCH Command for Controlling What Kind of Information Is Returned
- RFC 4735 Example Media Types for Use in Documentation
- RFC 4730 A Session Initiation Protocol Event Package for Key Press Stimulus
- RFC 4736 Reoptimization of Multiprotocol Label Switching Traffic Engineering Loosely Routed Label Switched Path
- RFC 4729 A Uniform Resource Name Namespace for the Near Field Communication Forum
- RFC 4737 Packet Reordering Metrics