How to Make a Phone an Intercom

Written by brenda barron Google
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How to Make a Phone an Intercom
An old phone can make a functional intercom. (Telephone Intercom Cable Station image by Charlie Rosenberg from

If you're looking for a fun weekend project or find yourself needing to communicate across the expanse of your house, building an intercom might be a good idea. The good news is creating and installing this device doesn't have to be costly and just by using old phones, you can craft a functional intercom that allows you to say hello from one room to another.

Skill level:

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Things you need

  • 2 telephones
  • Phone wire
  • 2 telephone sockets
  • Loose wire
  • 12V battery
  • Wire cutters
  • 680-ohm resistor
  • Battery jack
  • Soldering iron
  • Solder
  • Screwdriver

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  1. 1

    Strip about two inches from a middle section of the phone wire. Cut the red wire from the two-inch middle section and strip the wire's ends. Connect and solder one end of the red wire to a battery jack's connector or terminal.

  2. 2

    Cut a two-inch piece of loose wire and strip the coating from both ends. Connect and solder one end of the loose wire to the open battery jack's connector or terminal. Solder the other loose wire end to an 680-ohm resistor. Attach the loose end of the resistor to the open red wire you stripped earlier. This will close your circuit.

  3. 3

    Strip both ends of the phone wire. Solder and connect the like-coloured wires to the same wires of your phone sockets. Plug a corded phone into each of the phone sockets and install the battery into the battery jack. Lift the phones off their receivers to activate the intercom.

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