[asterisk-dev] DTMF detection and generation code

[Andrew Kohlsmith]

On Sunday 23 April 2006 16:42, Iain Barker wrote:
> A visitor presses the intercom/doorbell, and is actually initiating a POTS
> call from the entryphone to the listed phone number of the tenant. The
> tenant answers their phone, talks to the visitor, and then if they want to
> open the door they press a single DTMF key. The door latch is 'buzzed open'
> only for the duration of the keypress.

Not in my experience; the door is buzzed open for a fixed duration... 
typically 15 seconds.  If the person didn't get the door open in that time 
they call again.

-A.