RTP Payloads for Telephone Signal Events

Document Type Expired Internet-Draft (avt WG)
Author Scott Petrack 
Last updated 1998-11-23
Stream Internet Engineering Task Force (IETF)
Intended RFC status (None)
Expired & archived
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Stream WG state WG Document
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This note describes two RTP payload formats for in-band telephony signal events (TSE) such as DTMF, dial-tone, ring-tone, off-hook, SIT, etc. One payload is designed to carry a named signal, and the other is designed carry a compact representation of actual audio waveform cadence to be played. The two formats are independent, but they can be used together very usefully within redundant audio payloads; this enables highly efficient and robust transport of telephony network signal events along with a representation of the actual audio media associated to the signal events. Acknowledgements: This internet draft is an extension of H. Schulzrinne's draft ietf-avt-dtmf-00.txt and borrows heavily from it (including copying actual text). The main extensions appearing in this draft are as follows: a) many other telephony call progress tones and signal events have been added to the original DTMF and flash-hook of ietf-avt-dtmf-00.txt (an attempt has been made to align this with [MGCP] and [E.180 supp2] b) a second payload is defined which carries a highly compact frequency representation of the audio waveform of the signal; c) a few clarifications about reliability and redundancy, including how the two payloads will work together. Acknowledgement is also due to [MGCP]; part of this draft is an attempt to use RTP to provide the signal transport required by MGCP, in a way which can be reused by a large class of applications.


Scott Petrack (scott.petrack@metatel.com)

(Note: The e-mail addresses provided for the authors of this Internet-Draft may no longer be valid.)