Open a 2-wire intercom with your phone
Digital 2-wire intercoms are the ones that get on worst with smart intercom openers. SoundKey works with them because it doesn't speak their language: it presses the door-release button, just like you do.
Why Nuki Opener and Ring Intercom don't work with many 2-wire systems
In a 2-wire system, every flat shares the same two cables. They carry the voice, the call to each home and the command to open the door, encoded with each manufacturer's own protocol, and sometimes encrypted.
Nuki Opener and Ring Intercom connect to those cables and mimic the signals. To do that they need to know each brand's protocol. Many they don't, and Nuki itself admits that some systems will never be compatible. Known cases:
- Fermax Duox and Duox Plus: Nuki is not compatible.
- Comelit Simplebus: Nuki lists it as not compatible.
- Golmar Plus, Uno and G2+: Nuki is not compatible.
- Tegui M72 and Urmet 1122/31: Ring is not compatible.
How SoundKey does it
SoundKey stays off the bus. It listens for the buzzer with a microphone and, if it's authorised at that moment, closes the door-release button's contact with a relay for an instant. To the intercom, it's exactly the same as pressing it with your finger.
So the only requirement is that the door-release button is a physical push button (one that goes down). Touch buttons are in development.
2-wire vs 4-wire intercoms
| Analogue (4+n wires) | Digital 2-wire | |
|---|---|---|
| Cables | 4 shared plus 1 per home | 2 for the whole building |
| Signals | Simple electrical signals | Encoded by each manufacturer |
| Buildings | Older ones | New builds and refurbishments from the last 15–20 years |
| Nuki / Ring | Usually work | Many are not compatible |
| SoundKey | Compatible | Compatible with a physical button |
Questions about 2-wire intercoms
How do I know if my intercom is 2-wire?
Lift the intercom off its wall bracket and look at the terminal block on the back: if only two wires come in, it's 2-wire. These are usually handsets with a door-release button and one or two more buttons (light, concierge), from brands such as Fermax (Duox), Tegui (Serie 8), Golmar (G2+) or Comelit (Simplebus).
Do I need a new 2-wire WiFi intercom?
No. Manufacturers sell WiFi monitors that replace yours, but they cost between €240 and €375 and need an installer. SoundKey is added to the intercom you already have.
Do I have to touch the building's wiring?
No. SoundKey's two wires go to the door-release button inside your intercom handset, not to the building's bus. Your neighbours won't notice a thing.