RTP Payload for DTMF Digits, Telephony Tones, and Telephony Signals
RFC 4733
Document | Type |
RFC - Proposed Standard
(December 2006; Errata)
Obsoletes RFC 2833
|
|
---|---|---|---|
Authors | Henning Schulzrinne , Tom Taylor | ||
Last updated | 2020-01-21 | ||
Stream | Internent Engineering Task Force (IETF) | ||
Formats | plain text html pdf htmlized (tools) htmlized with errata bibtex | ||
Stream | WG state | (None) | |
Document shepherd | No shepherd assigned | ||
IESG | IESG state | RFC 4733 (Proposed Standard) | |
Action Holders |
(None)
|
||
Consensus Boilerplate | Unknown | ||
Telechat date | |||
Responsible AD | Cullen Jennings | ||
Send notices to | csp@csperkins.org, magnus.westerlund@ericsson.com |
Network Working Group H. Schulzrinne Request for Comments: 4733 Columbia U. Obsoletes: 2833 T. Taylor Category: Standards Track Nortel December 2006 RTP Payload for DTMF Digits, Telephony Tones, and Telephony Signals Status of This Memo This document specifies an Internet standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the "Internet Official Protocol Standards" (STD 1) for the standardization state and status of this protocol. Distribution of this memo is unlimited. Copyright Notice Copyright (C) The IETF Trust (2006). 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. Schulzrinne & Taylor Standards Track [Page 1] RFC 4733 Telephony Events and Tones December 2006 Table of Contents 1. Introduction ....................................................4 1.1. Terminology ................................................4 1.2. Overview ...................................................4 1.3. Potential Applications .....................................5 1.4. Events, States, Tone Patterns, and Voice-Encoded Tones .....6 2. RTP Payload Format for Named Telephone Events ...................8 2.1. Introduction ...............................................8 2.2. Use of RTP Header Fields ...................................8 2.2.1. Timestamp ...........................................8 2.2.2. Marker Bit ..........................................8 2.3. Payload Format .............................................8 2.3.1. Event Field .........................................9 2.3.2. E ("End") Bit .......................................9 2.3.3. R Bit ...............................................9 2.3.4. Volume Field ........................................9 2.3.5. Duration Field ......................................9 2.4. Optional Media Type Parameters ............................10 2.4.1. Relationship to SDP ................................10 2.5. Procedures ................................................11 2.5.1. Sending Procedures .................................11 2.5.2. Receiving Procedures ...............................16 2.6. Congestion and Performance ................................19 2.6.1. Performance Requirements ...........................20 2.6.2. Reliability Mechanisms .............................20 2.6.3. Adjusting to Congestion ............................22 3. Specification of Event Codes for DTMF Events ...................23 3.1. DTMF Applications .........................................23 3.2. DTMF Events ...............................................25 3.3. Congestion Considerations .................................25 4. RTP Payload Format for Telephony Tones .........................26 4.1. Introduction ..............................................26 4.2. Examples of Common Telephone Tone Signals .................27 4.3. Use of RTP Header Fields ..................................27 4.3.1. Timestamp ..........................................27 4.3.2. Marker Bit .........................................27 4.3.3. Payload Format .....................................28 4.3.4. Optional Media Type Parameters .....................29 4.4. Procedures ................................................29Show full document text