[Asterisk-Users] Integrating door intercom?

[Joseph Gutowski]

Haven't ever seen one of these, but from the description it should be
quite happy connected to a FXO (provided your Dial plan knows what to
do with incoming calls on this line, of course).

Make sure that the DTMF is passed correctly from whichever phone you
answer on out to the Dial-Phone box. If your DTMF is properly
configured, it should work. If you can call the bank and have no
problem with DTMF, likely you're configured correctly.

Since it uses (*) to open the door, watch out for other things in your
dial plan or phone which will intercept the * and not send it back out
over the line. Also watch out for situations (like SIP events for
tones) where the tone is a predefined length, no matter how long you
press the button. It looks like the box will do 3-seconds minimum when
it gets the tone, so it likely won't be a problem.

I had an ATA which wouldn't let me send an *, it was locked in the
firmware that * was a service code interpreted by the ATA.  It could
be worked around with a crafty extensions configuration, but annoying
as hell that I couldn't turn off this "feature".