Integrating 4-wire intercom with Smart Things?

(Tony Rielage) #1

I’m very new to all this, so please bear with me. I have a suite in a mixed use building, and we have a 4-wire intercom. I want to see if I can add a momentary switch to the current intercom so that I can, for instance, set up a time window for the janitorial staff or other visitors, and when they buzz the intercom for my suite, the intercom “door” button automatically buzzes and lets them in. I don’t know if that’s feasible, and I am not tech-savvy enough to write up the code for myself, so getting a starting point is basically where I am at this point. Thanks in advance for any help you can provide!


It can be done, but not just with code. You’ll have to wire in a device to the circuit that can communicate with SmartThings.

You can see how other people have approached it by using the quick browse lists in the community – created wiki, looking under project reports, and checking the “doorbell projects” list. There are a couple there. :sunglasses:

(Tony Rielage) #3

Ah, okay, great. I appreciate it. So, dumb question- do you have to wire in two separate devices, one to “hear” when the intercom buzzer has been buzzed, and another to trigger the door buzzer itself? I was thinking about the Levitron 30 amp load control module, here:

I thought that would work (potentially) to trigger the buzzer to let people in, but I don’t know what to use to “hear” the buzzer being buzzed from the front door in the first place.

I’m hopeful this works out, because wiring other stuff to the SmartThings hub would be very helpful for my business.

(Robin) #4


A) you’ll need a device to ‘hear’ the doorbell. The required device will depend on the input voltage and frequency you are picking up using a multi-meter. If it’s a nice clean on/off signal less than 16v, a mimolite should work (and can also be used to do part B below with one device). If it’s an audio (speaker) signal you’ll need to go about it via different route which I can go into if required.

B) You could use one of a veriety of smart (dry contact) relay switches to ‘press’ the door release button based on the message sent by (A)… this can be processed by the CoRE smartapp so no code skills required.

(Jon) #5

Hi RobinWinbourne

I’m new to smartthings and have an added feature and wonder if you may shed some light.

Similar to OP, I have an intercom phone too but it’s an audio/video door entry phone intercom.

Was wondering if you help how one goes round to connect to smartthings for:

1.) Audio Buzzer which allows voice communication on existing unit

2.) Video

3.) Unlock mechanism

I’m planning to alter my current phone to add in the additional features so I can be notified via phone or tablet.

(Robin) #6
  1. detecting the audio buzzer in order to trigger a ST event is doable following a method similar to this:

But two way audio is, I think, beyond the capabilities of ST right now.

  1. theoretically doable but will require a video encoder to MPEG device, typically a big black box normally associated with old fashioned CCTV… not practical really and won’t be all that reliable either.

  2. if the door release button is just a push to make (retractable) switch then this part is easy enough. You’ll need a smart air gap relay, (preferably with a built in timer) wired in parallel with the original switch. in the UK I would reccomend the Fibaro relay switch but not available in the US.

(Jon) #7

Thanks Robin. Ill start a mini project to test it. Shame we cant do a bidirectional audio communication as yet

(Tony Rielage) #8

Thanks a ton for the info. I’m not sure if the input voltage is less than 16v. I have a voltage tester and can check, but I’m not sure what to connect it to (sorry, not as savvy with the electrical stuff as I’d like to be).

If it does require an audio signal, which it might be, what would I need to do in that case? Just trying to sort out what I need to actually purchase before I bring in an electrician to hook it all up properly.

(Robin) #9

See the the link in item 1 above… you need a cheap audio sensor.

(Tony Rielage) #10

Thanks for that info. I’m planning to test the voltage tonight, but I honestly don’t know what to connect to what. Do I need to see what the voltage is when the circuit is on (like when someone buzzes, or when I buzz them in?), or can I just connect it and see what voltage is going through the panel? Sorry for all the questions- just very new to this.

(Robin) #11

Buzzing someone in:
Two wires go to button. No need to test, it will be a push to make button so this just needs to be replicated using a smart relay.

When someone rings the bell:
Test voltage applied to the speaker / buzzer by connecting a probe to each of the two wires connected to the speaker / buzzer.