[asterisk-dev] DTMF end accepted without begin

John Aughey jha at aughey.com
Mon Dec 3 11:55:28 CST 2007


We actually get both the "wobble" detection (multiple tones detected with
one button press) and missing detection (press 201 and it detects 01 missing
the 2).  The suggestions on voip-info have not yet helped and the lack of
DTMF_BEGIN events concern me.  It's also not clear right now where the dtmf
detection is done, if it's in the zaptel-1.4.6 code base or within
asterisk-1.4.14/main/dsp.c.  They both seem to do tone detection.

John

On Dec 3, 2007 10:31 AM, Daniel Hazelbaker <daniel at highdesertchurch.com>
wrote:

> On Dec 2, 2007, at 5:35 PM, John Aughey wrote:
>
> > The begin frames (and associated end frames) are helpful to filter
> > out short dtmf reads.  There's even a #define which specifies the
> > minimum length of a dtmf tone.  One problem we're having is multiple
> > dtmf detections on a noisy cell phone connection, which should be
> > mostly filtered by knowing the begin and end time so that the length
> > can be properly measured and filtered if needed.
> >
> > John
>
> If you are running 1.4.15 (it should apply down to .12 as well I
> believe) then you can try this patch.  We have a similar problem at
> our site, except it is due to a junky NEC that is currently the front-
> end to the Telco.  Tones would have a drop-out in the middle of them
> so Asterisk was detected double digits.  i.e. they dial 235 and it
> reads 2335.  With this patch the "wobble" tones are almost never an
> issue anymore.
>
> <http://www.blueboxmoon.com/bitweaver/blogs/view_post.php?post_id=10>
>
> Daniel
>
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