[SIPForum-discussion] DTMF tones and digit in SIP

[Wang Yi]

Sometimes using Info may cause problem comparing to RTP. RTP and SIP message
Info may transmit via different route. So they may not be synchronized very
well. For example, if VM must wait DTMF says 1 ,then begin to recorder RTP
to voicemail. what about if DTMF carried by Info arrived lately? several
seconds at the begining of voicemail will be lost wrongly.

2007/9/13, MULTACH, JEFF (ATTLABS) <jm5212 at att.com>:
>
> It is unclear if the question is in regards to the reason for DTMF or
> the method used to carry it.
>
> Along the first path of discussion, DTMF signals in the middle of
> applications can be distorted, especially when using codecs which
> perform compression. Therefore there is a need to have a method to carry
> this in a manner so that they can be accurately reproduced.
>
> This is true not only for IVR type systems (including voice mail
> systems) but also for many alarm systems, a case which is often
> overlooked.
>
> Alarm systems have multiple ways of transmitting their signals based on
> their design. One of which is using a rigid DTMF sequence, so not only
> does recognizing the DTMF tone become important but also the duration of
> that tone.
>
> -----Original Message-----
> From: discussion-bounces at sipforum.org
> [mailto:discussion-bounces at sipforum.org] On Behalf Of Sai Prabhakar
> Varanasi
> Sent: Thursday, September 13, 2007 1:56 AM
> To: discussion at sipforum.org
> Subject: Re: [SIPForum-discussion] DTMF tones and digit in SIP
>
> DTMF digits are mainly useful for IVR applications.
>
>
> Thanks & Regards,
>
> Sai Prabhakar Varanasi,
>
>
> -----Original Message-----
> From: discussion-bounces at sipforum.org
> [mailto:discussion-bounces at sipforum.org] On Behalf Of Sumanta Sen
> Sent: Thursday, September 13, 2007 9:19 AM
> To: discussion at sipforum.org
> Subject: [SIPForum-discussion] DTMF tones and digit in SIP
>
> Hi All,
>
> What is the practical purpose of carrying DTMF digits in SIP using INFO
> or
> RTP Payload ?
>
> Thanks,
> Sumanta
>
>
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-- 
王毅
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