[Asterisk-Users] Changing DTMF mode depending on codec chosen

[Rich Adamson]

> Thanks for the very detailed way to setup BV with *.. Actually, I've had
> asterisk and BV working both incoming and outgoing since May of last year..
> You are quite correct, though.. I'm by no means an expert in *, but there
> was a good week or two of scratching my head back then to try and get it to
> work reliably with BV.. I have to admit, once it works, it just works,
> though (Minus the irriating sound problems, but that isn't a BV specific
> problem)..
> 
> I was more curious if there was a way to detect which codec was chosen for a
> specific call, and be able to adjust the dtmfmode accordingly.. If you know
> of any way to have * detect the codec and switch dtmfmode on the fly (per
> call), I'd love to hear how to do that.

I don't believe that is possible as the codec negotiation process
happens before dropping into an extensions.conf context, and that
would be about the only place I can think of where you'd attempt
to change dtmf modes.

Guess you could file a bug (feature) request to force dtmfmode=rfc
when g729 is negotiated as dtmfmode=inband isn't at all valid. But,
you couldn't do the same for g711.

> As you aptly pointed out, BV isn't consistant in their g.729 implementation.
> It works sometimes, others I get ulaw.  As with you, bandwidth is precious,
> so I would love to save it whenever possible.. But, if I cannot make the
> dtmfmode reliable, I'll have to stick with ulaw.
 
Unless you're tied up with a BV number that can't be changed, I'd
just change providers to one that supports iax/gsm.