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Door Box System Main Controller

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Main Controller for Door Box System
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Door Box System Main Controller

This Controller is the HEART of the Door Box System!


The wall mount Controller is normally mounted near where the phone lines come into the building, or near the phone system.

Each Door has a Distinctive Ring, different from the regular ring on a CO line. Note that you wouldn't hear the distinctive ring on most phone systems, because the phone system makes its own ring (it doesn't pass the cadence from the phone line through to the ringers on the phones).

If a phone system can't pass the distinctive ringing on to the phones, and the customer really needs to know whether it's the front or back door ringing, the solution is to use two Controllers, one for each door, and have them ring in to separate CO lines on the phone system (this is still pretty inexpensive!). For example, CO5 for the front door, and CO6 for the dock door.

You can bridge up to two Door Boxes to each Door connection on the Controller. That lets you have up to 4 Door Boxes on each Controller

BUT WAIT, there's more...

You can put up to four Door Box Controllers in-series with each other. Just go from LINE OUT to LINE IN from Controller to Controller. With 4 Door Boxes per Controller (2 on each Door port), that means you can have up to 16 Door Boxes ringing in on 1 Line!

Note that if you put two Door Boxes on a single Door Box port, the same sound will come out of both Door Box speakers, and you'll hear the ambient noise from both doors (and the volume will be a little lower because they are bridged together).

Easy Installation!  The telephone line and/or telephones connect to either the modular jacks, or screw terminals (jacks and screw terminals are bridged together internally).

There are two screw terminals (+ and -) for each of the two Doors.

The Controller installs in minutes!

Use LINE IN for the telephone company phone line if you are sharing the Door Box System with a phone line in a home. LINE OUT goes to all of the phones in a home, or a phone system in an office.

NOTE: Do not share a phone line if the Door Box System is on a line on a phone system. Because the line on the phone system can be put on hold, there would be nobody to hear the Call Waiting tone when someone is at the door, and the line is on hold. That would lead to service calls where the customer complains that someone was at the door, but they never heard the phones ring.

Call Waiting should NEVER be put on a CO line on a phone system for that reason. It's very hard to diagnose No Answer problems caused by Call Waiting on a service call!

Use the Controller to make your phones ring!   You don't even need a Door Box if you just want to ring your phones when something happens!

  • When you short the Door 1 or Door 2 contacts through a 300 ohm resistor, any phones you have connected to LINE OUT will ring!
  • Stick an electric eye on your driveway, and the phones will ring every time someone comes up the drive
  • All you need is something that provides a dry closure to make your phones ring
  • If you also have a Door Box, put the Door Box on Door 1, and the dry closure on Door 2 (you'll hear a distinctive ring on single line non-cordless phones)


Controller comes with an AC plug (not a power cube). The Controller MUST be installed in an area protected from the weather (temperature and moisture). You should also install an AC Surge Protector, and Lightning Protection if it's connected to a phone line or the Door Box goes outside the building to a gate.

NOTE:  Electronic Devices Attached to Phone Lines Need Lightning Protection!


If the Door Box System is attached to a phone line in a home, it can be damaged during a lightning storm.

The Phone Company provides lightning protection where their wires enter a home, but it's designed to prevent damage to the old style phones that weren't electronic. Modern electronic phones or phone equipment is much more sensitive to lightning than older phones.

If your Door Box is mounted to the side of the building, and the wires don't travel outside the building, you don't need lightning protection on the wire coming from the door. If the Door Box is located at a gate, away from the building, you absolutely need lightning protection on the pair of wires before it gets to the Controller.

Even if you run the cable to the gate in a metal conduit, you still need lightning protection on the pair from the door, at the controller.

Be Sure to Check Out Our Lighting Protection!

You need our MLP-270M or MLP270T for the phone line, and the MLP-030T and Door Box TVS for each Door Box where the wires go outside the building.


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