[SIPForum-discussion] What is the function of telephone-event?

[Steve Langstaff]

...Because if you have a low bitrate codec it may distorting DTMF beyond
recognition (recognition by the IVR equipment, not the human ear).


________________________________

	From: Andrea Puddu [mailto:androjoker at hotmail.com] 
	Sent: 06 March 2008 14:09
	To: Steve Langstaff; discussion at sipforum.org
	Subject: RE: [SIPForum-discussion] What is the function of
telephone-event?
	
	
	Thanks Steve.
	
	Why did you talk about low bit-rate codec? I understood the
matter about dtfm out of band, but it is not clear to me why it should
impact low bit rate codec (e.g. g729).
	
	Thanks,
	
	Andrea
	




________________________________

		Subject: RE: [SIPForum-discussion] What is the function
of telephone-event?
		Date: Thu, 6 Mar 2008 05:01:34 -0800
		From: steve.langstaff at citel.com
		To: androjoker at hotmail.com; discussion at sipforum.org
		
		
		"telephone-event" is a method for passing e.g. DTMF
signalling in an RTP stream.
		 
		The "101" (or any payload type in the range 96-127)
refers to a dynamic payload type.
		 
		So a stream that negotiates to use "101 telephone-event"
may e.g. pass keypresses
		using RTP payload type 101 rather than "in-band".
		 
		The risks you face in removing telephone event support
are that if you are using a
		low bitrate codec such as G.729, or you are using
equipment that does not expect
		to see DTMF "in-band" then users may lose the ability to
control e.g. IVR equipment.


________________________________

			From: discussion-bounces at sipforum.org
[mailto:discussion-bounces at sipforum.org] On Behalf Of Andrea Puddu
			Sent: 06 March 2008 12:15
			To: discussion at sipforum.org
			Subject: [SIPForum-discussion] What is the
function of telephone-event?
			
			
			Hello guys,
			
			as the network here does not completely support
"telephone event" in SDP they asked me to set up phones to not include
"telephone event".
			I have looked at some RFCs .... but I couldn't
understand what the telephone events are useful to.
			
			Do you see any risk to remove the telephone
event, in particular the 101 telephone event?
			
			thanks 1000.
			
			Andrea
			

________________________________

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