I recently moved into an old apartment and found this contraption in a closet, with wiring going in different directions around the door frame. Some of the wires are cut in places mid-wall and have been painted over into the wall. Right adjacent to it, by the closet door, is the equally ancient buzzer I use to let people into the building. Both the audio AND video feedback don't work -- I just press the unlabeled button for entry; it has no telephone capability.

My concern with the wiring is that occasionally my buzzer will go off for a split second even though my door isn't being rung (when it IS my door, the screen turns on too, so I'd know). The screws on the contraption are labeled "RGBY," which a quick Google suggests landline telephone wiring -- except! -- there is no phone jack in my apartment.

So: Is this just a remnant of previous landline wiring? Can it be causing the false buzzing? What's that hole in the center? Just, what is it overall?

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3 Answers 3


The device is simply a junction block for telephone wiring. Normally, it would have a square cover that's held in place by a screw that goes into that center hole.

The false buzzing cannot be caused by this alone; there must be wiring errors elsewhere in the building.


That's an old-fashioned terminal block used for making hard-wired telephone wiring connections. The hole in the center is used to screw down the cover plate which is missing.

It is plausible your intercom/buzzer uses this wiring given the positioning, but I don't see any reason to believe this terminal block is particularly likely to be part of the problem. (A model number for the intercom might help find out whether it is likely to use telephone style wiring or not.)

It might be helpful for diagnosing the problem if you were to start investigating how the equipment works and whether the fault is in your apartment or outside it, because it is an easily accessible point at which you can separate the circuit. But that is irrelevant unless you have test gear and knowledge.

  • With the age of the system it could be close to end of life, the paint bridging the terminals is not a good thing and could be causing some problems but probably close to end of life
    – Ed Beal
    Dec 1, 2017 at 14:36

for what its worth a single POTS phone line would have just used the red-green pair and it would not be unusual for the black/yellow to be re purposed for something else.

  • Like an Alarm system, or perhaps a buzzer..
    – Ken
    Dec 2, 2017 at 10:34

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