Open an Old Intercom With My Android Phone

Hey there,

Its my first time here.

I need to connect the our building intercom to my phone. The goal is to be able to open the door using the phone remotely.

Our building is old and so as our intercom system and I can not replace it.

Any idea how to start such a project?

Take a look at the Fibaro Universal Binary Sensor:

It’s often used to adapt older alarm systems to Z-Wave if there is any output from the old system which could serve as an “on or off” detection.
If you can get the actual state of your intercom through this sensor you could attach a relay to your intercom to open the door.

I had a similar problem. The available documentation for our intercom was very old and incomplete, hence my very hacky solution was:

  • solder connectors to the cables carrying power to the video display part of the intercom. The power goes on when the front door buzzer is pushed. I have those connectors linked to a relay, and that triggers a Fibaro sensor so I know when someone rings the buzzer
  • solder connectors to the intercom PCB in parallel with the “open door” switch, and then control this with a Fibaro relay

Works very nicely. Next objective is to attach a raspberry pi to the composite video cable that goes into the entryphone, so I can view it from openhab

Hello @dan12345,

Im trying to do a similar solution, may i ask which fibaro relay are using?

My intercom works with 12v DC, i guess the relay fgs222 for example won’t work…
Are you using the universal sensor?

I have mains power nearby which I use to power the FGS222. Annoyingly there don’t seem to be any zwave relays that work on low voltage DC. The universal sensor description is misleading - the relays are simply triggered by the inputs, and can’t be operated independently.

By way of a quick update: taking video off the composite video turned out to be easy - then a raspberry pi with cheap USB video dongle streams it using mjpg-streamer.

Taking audio off the entryphone was also easy, and I used a mumble server and client to be able to speak over the entryphone remotely. However this creates a truly ridiculous echo effect. Need to find something to fix that. For the moment I just have pre-recorded MP3s saying eg “please leave the package on the doorstep” which openhab can trigger remotely.

Perfect, thanks for the quick update.

So you were connecting the relay with an alternative input connection, using the 12v DC as the input to the be outputed using the two switches, right?

I will try the same solution then and report back :slight_smile:

Many thanks again for the quick response…

I was not very clear:

the 12 VDC is sufficient to power the fibaro general input device. I connect that to a relay that’s driven by the entryphone energising the video screen DC power (which goes live when someone rings the buzzer)

then have a separate fibaro double relay device powered by the mains, which controls the “entry” button via some soldered connections


I think im somehow lost now :smiley:
Which sensors are you using exactly? I thought the fibaro relay switch is enough.
Do u have some kind of schematic or drawing shows the connections? It will be great.

I understood that i should connect 220v to the main power of the fgs-222 then 12v to the free input pin, then the Door buzzer and the intercom bell button to S1, and S2.


I didn’t think the FGS-222 had a usable input; I use an FGS-222 for my outputs, and a separate Fibaro univesral binary sensor for the input

Well, i ended up using the Wemo Maker + a car relay.

It works perfectly up till now :slight_smile:


Just to add that there is now a low voltage zwave relay device, albeit 24VDC not 12