[asterisk-users] PBX to gate interface

[Gordon Henderson]

On Wed, 18 Mar 2009, Chris Mason (Lists) wrote:

> How does a Push-to-talk intercom interface with Asterisk?

I think the generic answer is "expensively".

If Xorcom made just the IO part of their channel banks then it might be 
cheaper, however ...

What I've seen so-far is an intelligent box with what's effectively an 
analogue phone interface that you connect to an FXS port. The intercom is 
basically a "hardened" phone - you push the button, the phone comes 
off-hook and dials a pre-set number. (or just goes off-hook and expects 
"bat phone mode"). The other end can send DTMF codes down to activate a 
relay which can then power a door opener - or not.

Some boxes have a keypad, allowing a local code to be "dialled" which 
activates the relay directly, and some can dial internal extensions, 
letting the person who answers key in the unlock code. Some can even 
answer a call and listen for tones, so anyone could call the door-phone 
and unlock the door (eg. from your mobile phone while standing outside)

But sometimes you just want a relay connected to the asterisk box because 
you have everything else - I eventually found a German company doing USB 
mains power cyclers which you could control from a Linux command-line 
program, so no need for a xorcom box after all. The options are endless as 
are the prices you can expect to pay. It all depends on the "intelligence" 
you need in the door.

Ones I'm looking at right now:

http://www.voipon.co.uk/2n-analogue-helios-door-entry-system-c-22_276_279.html

Thats sort of the entry level. At least they have prices on their website 
unlike the recently posted North supply Link! (Why do sites do that?)

Gordon