[asterisk-dev] ASTERISK - DTMF Inband Handling

[bala murugan]

Thanks Matt ,

see response inline




On Fri, Jul 14, 2017 at 4:50 PM, Matt Fredrickson <creslin at digium.com>
wrote:

> On Wed, Jul 12, 2017 at 10:47 AM, bala murugan <fightwithme at gmail.com>
> wrote:
> > Hi ,
> >
> >  can anyone provide answers or comments on the below
> >
> >  1.   What is the expected minimum and maximum silence duration between
> the
> > dtmf tones.
>
> I think that depends on how you're playing DTMF tones within Asterisk.
> For tones utilized in the case of sending call address data to setup
> the call, the answer is dependent on the channel driver.  For tones
> that are bridged between calls that are already up and active, you can
> potentially have variable length tones, depending on where the DTMFs
> are coming from.  If you're using an application in Asterisk to play
> tones depending on the underlying API the answer might be different as
> well.  Which case are you concerned about?
>


> [Bala] This is expected through an External IVR Application that talks
> through Asterisk AGI Interface which plays prompt and expects DTMF on agi
> response .
> This is not a bridged call . Asterisk is only the receiver of Inband DTMF
> on G711 ulaw and send the same to the external IVR application via AGI
>  using chan_sip Driver
>
     Need to know if there is any expected  fixed silence (max or min)
duration between each tones required for reliable processing of the tone
that comes from  gateway/switch(which is a source sending inband dtmf
tones).


> > 2. mindtmfduration = 80msec in /etc/asterisk/asterisk.conf what is the
> > significance of this parameter ? .  Is there any maxdtmfduration or
> > highwatermark configuration or limitation in handling the DTMF tone's
>
> If a passed through DTMF event on a bridged call that's already up
> receives a dtmf indication that is shorter than the mindtmfduration,
> Asterisk will extend the length of the tone to be at least
> mindtmfduration milliseconds long.
> [Bala] Can this be explained more on how the behavior would be for IVR
> kind of application that's implemented using AGI.
>


> > 3. can it handle the DTMF tones  ranging in the 180-210 ms duration . The
> > reason is we are experiencing DTMF issue and all the tones that sent to
> > asterisk are in this range.
>
> I can't think of a reason why that would be an issue.
>
   [Bala] We see the tones are missed if there is a delay of 400msec
between tones with the tones duration ranging  180-210ms.

   so looking for defined or asterisk expected standard length/duration and
delay/silence duration between each tones Inband DTMF benchmark for
reliable DTMF processing .

> --
> Matthew Fredrickson
> Digium, Inc. | Engineering Manager
> 445 Jan Davis Drive NW - Huntsville, AL 35806 - USA
>
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