North American POTS phones have about 50 volts between tip and ring, which drops significantly when the phone goes off-hook (I can't remember how much exactly, but I had a voltmeter circuit hooked up to detect when another extension went off-hook at my house) and a ring was a 25hz AC signal at about 90 volts superimposed over-top of that. You could maybe run a SIP softphone or an Asterisk server on a Raspberry Pi and use some custom code to toggle one of the Pi's GPIO pins to press the relay button in response to touch tones on your end.
And I’m assuming that I could do the same again with some sort of ATA or SIP server that can activate door relays? I have already hacked an IoT relay to the door release to allow me to remote unlock the security gate/lobby door.
It's only a single pair plus a completely different circuit to buzz someone in, you mean And ‘expert’ is wildly overstating things. I am the subject matter expert for our building’s intercom. And there is no one to ask for help on this system but me. There is no keypad etc to allow couriers delivery drivers entry. Just buzzers for each of the 11 apartments and nothing else. But if there was a way via VOIP solution to trigger a door release with a key press on my phone that would me perfect.ĮDIT 3: This is the cheapest, least featured, building intercom possible, IMO. That’s all there is to it recently.ĮDIT 2: I could live without the door release as I already have door release solution. And a button on the handset in the apartment releases the security gate and lobby door. The button at the gate rings the corresponding apartment.
Horribly insecure and vulnerable to eavesdroppers. Anyone who picks up their handset can hear/talk to anyone at the gate, as well as anyone else who has picked up their apartment handset too. NFI what model or anything though, sorry. Can anyone please advise if a commonly available ATA like ‘Cisco ATA 191 2 Port Phone Adapter’ would be all the hardware I need to connect my handset on my apartment buildings very primitive analog intercom to VoIP, so when someone buzzes my apartment at the front gate, it can call the programmed phone number?ĮDIT: It’s an Urmet solution.
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