[Asterisk-Users] Limit DTMF tones

[Steven Critchfield]

On Thu, 2004-11-04 at 13:59 -0500, Andrew Thompson wrote:
> Andrew Kohlsmith wrote:
> > On November 4, 2004 12:30 pm, Henry Devito wrote:
> > 
> >>The issue is the inmates have figured out a way to dial long distance
> >>numbers by calling different private phone numbers and using that companies
> >>DISA to complete calls. So in order to stop that I have to suppress dtmf
> >>after so many digits are dialed.  Any idea's?
> 
> If you configured a SIP phone to not transmit inband DTMF, would 
> asterisk translate that to inband DTMF when bridged to an inband DTMF 
> only connection, ie your POTS line?

Depends on the codec if it would be able to detect and therefore
squelch.

> Note: Just talking out of my head here, I've not actually tested this...
> 
> In any case, chan_sip would be much more likely to be hackable to make 
> DTMF quit working.

As long as asterisk is looking for DTMF, and it is connected, the best
place would be in the bridging where it is looking at the frames. As has
been posted before, when you are reading the frames as they come in, you
could just look at the frame type and decide whether it needed to be
sent or acted upon. In this case, acted upon could be dropping it to the
floor and replacing it with a silence frame of the proper duration.
-- 
Steven Critchfield <critch at basesys.com>