[asterisk-users] DTMF from TDM400P and X100P

[Tzafrir Cohen]

On Fri, Mar 02, 2007 at 01:48:21PM -0800, Yuan LIU wrote:
> >From: Tzafrir Cohen <tzafrir.cohen at xorcom.com>
> >Date: Fri, 2 Mar 2007 22:14:09 +0200
> >
> >On Fri, Mar 02, 2007 at 09:36:28AM -0800, Yuan LIU wrote:
> >> With one IVR payment system, I noticed quite a difference in DTMF
> >> transmission between these two cards.  The IVR missed nearly all digits
> >> from X100P, while receiving digits from TDM fine.
> >>
> >> Since neither card process or synthesize audio, what can the difference be?
> >>
> >> (This particular IVR has problem with some regular phone devices, too.)
> >
> >audio quality?
> 
> You mean from DAC?  That could make sense - altough the MODEM function 
> X100P is designed for would require it to be fairly accurate.  DTMF itself 
> is one of basic MODEM functions.

No. I mean: bad distortion of the analog audio that breaks the DTMF
detection (which is done in Asterisk).

> 
> >listen to the audio with e.g. ztmonitor.
> 
> Thanks for the input.  Have yet to put a sound card with TDM. (The IVR in 
> question is not my machine.)  I suspect that ztmonitor listens to the 
> digital output, though.

Record it to a sound file.

A simplistic but useful test is to play that very same sound file to a
phone and see if it "dials" the digits you have expected it to dial.

-- 
               Tzafrir Cohen       
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