[asterisk-gui] Greandstream IP phone

[David Kerr]

In the .conf file that you setup the extension for grandstream check for a
line...dtmfmode =
and try various settings... auto, inband, rfc2833, info

DTMF = Dual Tone Multi Frequency, a technical term for touch tones generated
when you press keys on your telephone.  dtmfmode setting tells asterisk how
to send/expect to receive signals as each key is pressed.

auto means asterisk will try and figure out which method to use.
inband means that an audible tone is send down the voice path... this
is susceptible to codec corruption. ulaw/alaw work, but other higher
compression codecs most likely will not.
rfc2833 means use the protocol defined in the internet rfc2833 document.
This is probably the most widely used method.
info means send a SIP INFO message.

Be sure to test whatever setting you select not just with your own voicemail
system, but also with other services at the far end of a trunk. For example,
call a company that you know has a touch-tone voice response unit and make
sure that your tones are understood.  I have found that some SIP trunk
services work with some dtmfmodes, but not others.  In the worst case
scenario it can even depend upon your service providers selection of their
backhaul provider... which may mean that it is dependent upon which number
you call (so if they route toll free numbers through one carrier, and local
calls through another, dtmf could be affected).

Personally, I have found that the only setting I can get to work reliably
for me is "inband" with ulaw/alaw codec. But your mileage may vary, and my
results could well be a symptom of the particular combination of trunk
carriers I use.

David

On Wed, Aug 12, 2009 at 9:34 AM, Bob Crandell <bob at assuredcomp.com> wrote:

>  I don't know what that means.
>
> Thanks
>
> Bob
>
>
> >>> tom <tomabroad at gmail.com> 8/11/2009 07:47 PM >>>
> maybe dtmf?
>
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