[asterisk-users] How to send DTMF down a channel

[Frank Church]

I followed my intuition and sent a DTMF tone via the D() option in the
dial command to the destination and that causes the voice to be
transmitted after the call is answered.

I also realised that the ringing tone to the destination does not come
up until I execute a SendDTMF command before dialling the destination.

>From that it appears that a command to issue a tone either before
dialling out or after the call is picked up is necessary for the
exchange of sound to take place, and I don't know whether that is a
bug, or a feature of the Asterisk design.

In verbose mode the call is interspersed with the output from the
complicated AGI script and that will make things difficult, I have the
problem (hopefully) solved now, but I will try to make the time to
send you the output of the script after I remove the AGI code from it.

In dial plan terms the idea is to generate a call file that contains
both the caller id of the caller and the destination, and when the
caller answers the call is routed to an AGI that extracts the dialled
number and dials it as though they were entered via DTMF. And it
appears that because no sound stream is generated through entry of
DTMF, no sound is transferred after the call is answered. Perhaps
trying something like that in a dial plan you create yourself will
reproduce the problem.

Thanks

Frank

On 9/15/06, Moises Silva <moises.silva at gmail.com> wrote:
> could you post the output of the asterisk console in verbose mode?
>
> In logger.conf
>
> [logfiles]
> console => notice,warning,error,verbose,debug
>
> Regards
>
> On 9/15/06, Frank Church <voipfc at googlemail.com> wrote:
> > The program in question is an adaptation an AGI calling card program.
> > It is adapted for callback by setting by channelling the callback call
> > into the context used for the normal inbound leg.
> >
> > When used that way entering the PIN and destination number via DTMF
> > works normally.
> >
> > I tried to implement sms/web callback simply by passing the
> > destination number and the callerid in call file's parameters, so that
> > the script can go straight to dialling the destination number without
> > prompting the caller for it.
> >
> > This method results in dead air when the call is answered at the
> > destination and it seems that the absence of DTMF tones for generating
> > the call is the cause.
> >
> > Logically it should work, why the call should result in dead air
> > because the destination number was not obtained through DTMF is what I
> > can't understand.
> >
> > It appears that the absence of DTMF stops the RTP from being
> > established to the destination number  or prevents the calls from
> > being joined. When I dial back to the calling  number I get the busy
> > voice prompt okay.
> >
> > Injecting the DTMF tones on the call channel is a really a kludge to
> > simulate actual key presses in the hope that the dead air problem will
> > go away and it .
> >
> > On 9/15/06, Moises Silva <moises.silva at gmail.com> wrote:
> > > Frank. PlayDTMF and SendDTMF is the same as pressing keys at the
> > > phone. Im not understanding well, can you please explain a practical
> > > scenario of how do you expect it to work, and how actually works? :)
> > > Thanks
> > >
> > > Regards
> > >
> > > On 9/14/06, Frank Church <voipfc at googlemail.com> wrote:
> > > > How do you specify the channel the SendDTMF is sent on, as it has to
> > > > be variable? I am able to use PlayDTMF  to send tones using the
> > > > manager interface - the tones come up okay but it doesn't work.
> > > >
> > > > My problem comes from a working callback script that I am trying to
> > > > adapt to web/SMS callback.
> > > >
> > > > The script is unchanged only that in the web/sms callback the
> > > > destination number is passed in the call file variables to allow it be
> > > > dialled after the callback is answered rather than being obtained via
> > > > DTMF.
> > > >
> > > > The destination call is made alright, but the called party only gets
> > > > dead air after the call is answered. It seems that the fact of
> > > > pressing the DTMF keys activates the sound channel in way that the
> > > > direct call back does not, which is why I am going through all these
> > > > hoops. I just hoped that sending some DTMF tones programmatically
> > > > would simulate the actual key presses.
> > > >
> > > > Do you have any ideas of what the problem might be?
> > > >
> > > >
> > > >
> > > > On 9/14/06, Moises Silva <moises.silva at gmail.com> wrote:
> > > > > http://www.voip-info.org/wiki-Asterisk+cmd+SendDTMF
> > > > >
> > > > > Regards
> > > > >
> > > > > On 9/14/06, Frank Church <voipfc at googlemail.com> wrote:
> > > > > > How can DTMF  be sent down a channel?
> > > > > >
> > > > > > I am thinking of method where say a channel id can be grabbed from
> > > > > > Asterisk Manager events and a DTMF signal sent down that channel,
> > > > > > through AGI, Asterisk Manager Interface or whatever?
> > > > > >
> > > > > > Is it possible to have a command in extensions.conf which can take
> > > > > > both the channel and the dtmf numbers as parameters and send the DTMF
> > > > > > signals?
> > > > > >
> > > > > > Frank Church
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