[SIPForum-discussion] DTMF

[dipanjan.dutta at aricent.com]

Hi Praveen,

DTMF information gets exchange after the media patch is  connected. It is 
also called in-band signaling,
The media path can be connected either through early media connection or 
through 200-ACK.

Further if any of the endpoint presses any digit in DTMF mode, this 
information is conveyed over media path using RTP. RTP header will 
indicate DTMF payload and inside the payload, the DTMF event would be 
encoded using RFC 2833.

While the UAs do initial signaling, they can a priori do a media 
negotiation for audio/telephone-event MIME type through SDP, so that 
anytime afterwards during a call, direct switching to DTMF in RTP can go 
on w/o issues.

thanks,
Dipanjan
                                                   




"praveen subbarao" <praveen_subbarao at rediffmail.com> 
Sent by: discussion-bounces at sipforum.org
05/21/2007 11:56 AM

Please respond to
praveen subbarao <praveen_subbarao at rediffmail.com>


To
"discussion" <discussion at sipforum.org>
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Subject
[SIPForum-discussion] DTMF






Hi All,

I have a doubt in SIP. Supposing that a SIP client wish to communicate 
with a PSTN client, then he will input the PSTN number. 

In SIP, where & how the DTMF information is carried. Which are the headers 
responsible for this? I rquest to knidly clarify.

Regards,
Praveen 



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