I-D ACTION:draft-ietf-avt-telephone-tones-00.txt

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This draft is a work item of the Audio/Video Transport Working Group of the IETF.

	Title		: RTP Payloads for Telephone Signal Events
	Author(s)	: S. Petrack
	Filename	: draft-ietf-avt-telephone-tones-00.txt
	Pages		: 11
	Date		: 23-Nov-98
	
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.

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