[asterisk-users] Double DTMF digits sent on IAX native bridge

[Steve Davies]

Replying to my own post...

Even more interesting is that the issue seems to be caused by the
Linksys ATAs that I am using to test with. If I use a mobile phone, a
landline, or a digital phone to originate the call, all seems happy.

If I use an ATA, it leaves just enough of the original DTMF in the
audio stream to be detectable by Asterisk, but it ALSO sends an
rfc2833 packet and both are detected and sent onwards!

I would still be interested in any ways to improve this!

Thanks,
Steve

On 5/3/07, Steve Davies <davies147 at gmail.com> wrote:
> This is very interesting. I am now getting this double-digit behaviour
> occasionally, and only on IAX channels (so far). Did anyone come up
> with a solution or a way to improve matters?
>
> The scenario where I get this is:
>
> PSTN -> Provider -> IAX -> Gateway -> IAX -> Customer
>
> So I will go and do some debugging to see where the extra packets are
> generated. Perhaps a simple change to prevent DTMF audio-tone
> detection on a channel that supports RFC or out-of-band DTMF
> transmission? Or perhaps some sort of DTMF debounce mechanism?
>
> Thanks,
> Steve
>
> On 3/6/07, Remi Quezada <remiq at monmouth.com> wrote:
> > Any ideas as to how I can fix this issue?
> >
> > Thanks
> >
> > Remi
> >
> > Remi Quezada wrote:
> > > Ok that makes sense, but I'm still getting double digits.  It seems to
> > > me that the DTMF digit is getting detected too late.  When the digit is
> > > pressed it seems like asterisk is passing the DTMF digit for a fraction
> > > of a second through the audio path and then sends the digit for however
> > > long your toneduration is set for.  I can hear this happening when I
> > > dial the digits myself, I hear some kind sound being cut off for a
> > > fraction of a second and then hear the DTMF tone pass.  So I guess this
> > > is why sometimes some answer machines are detecting double digits.
> > >
> > > Russell Bryant wrote:
> > >
> > >> Remi Quezada wrote:
> > >>
> > >>> I have two asterisk servers one is connected to the PSTN and the other
> > >>> one is connected to SIP users.  The two servers connect with each other
> > >>> using IAX.  When I have an incoming call from PSTN to the asterisk
> > >>> servers and have a forward to go back out to the PSTN the two IAX
> > >>> channel bridge together.  Now every time I dial a DTMF digit, the
> > >>> asterisk is sending two DTMF digits.  I enable debugging for iax and I
> > >>> do see it sending the DTMF digits two times.  Here is what I see:
> > >>>
> > >> The IAX debug that you show below only shows one of each digit.  For
> > >> each one, it shows Receiving the digit from one leg of the call, and
> > >> then transmitting it out the other.  I have spaced out your debug to
> > >> separate each digit.
> > >>
> > >> Each one shows ...
> > >>
> > >>    <----- digit ----
> > >>     ----- ACK ----->
> > >>     ----- digit --->
> > >>     <---- ACK ------
> > >>
> > >> which is exactly what is supposed to happen.
> > >>
> > >>
>