[Asterisk-Dev] HELP: DTMF signals screwed up by asterisk

[Asterisk Developer]

Steven,

thanks. actually that is not true, as it happens with MGCP as well. I'm not 
using any high compression codec, just plain g711/aLaw. I've recorded the 
wave form within asterisk, so the SIP/MGCP leg can't be the problem, it is 
definitely the E1/zaptel leg giving me the headache. i've tried to generate a 
call automatically using the spool/asterisk/outgoing queue, the waveform 
still gets deformed/screwed up.

bye
alf



---------- Original Message -----------
From: Steven Critchfield <critch at basesys.com>
To: Asterisk Developers Mailing List <asterisk-dev at lists.digium.com>
Sent: Wed, 15 Sep 2004 08:58:35 -0500
Subject: Re: [Asterisk-Dev] HELP: DTMF signals screwed up by asterisk

> On Wed, 2004-09-15 at 08:22, Asterisk Developer wrote:
> > hello,
> > 
> > I tried to use an analog emergency-call device. that device is a one-
button 
> > device that calls an emergency service like 911, it's for older people or 
> > people with disabilities. however, the device dials out to a remote 
server to 
> > login and gather some information. when the device dials the number, the 
> > server answers with a 2000hz tone and a DTMF sequence. that DTMF sequence 
is 
> > however totally screwed up by asterisk. each dtmf sequence is 80ms long, 
but 
> > asterisk cuts out 40ms from the sequence. it looks like:
> > 
> >  *******00000000000000*******
> >  0-----20-----40-----60----80---->
> >  ms                           
> > 
> > * = DTMF signal 
> > 0 = no DTMF signal
> > 
> > call direction SIP<->ZAP<->E1 (TE410P). I have a WAV file and a PNG image 
of 
> > the waveform. see http://www.jass.at/asterisk/
> > 
> > do we have a chance to turn off DTMF detection within zaptel/chan_zap?
> 
> You can't pass DTMF inband on the SIP leg if you use any compression.
> This means the problem you are experiencing is really in your SIP 
> leg of the call. Check your SIP device to see if it will let you 
> change the length of the DTMF tones.
> -- 
> Steven Critchfield <critch at basesys.com>
> 
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------- End of Original Message -------