Red Box

What is a Red Box?

When a coin is inserted into a payphone, the phone emits a set of tones. A red box is a device that simulates those tones, with the purpose of fooling the payphone into believing you have inserted an actual coin.

How do I build a Red Box?

Red boxes are commonly manufactured from modified Radio Shack tone dialers, Hallmark greeting cards, or made from scratch from readily available electronic components.

To make a Red Box from a Radio Shack 43-141 or 43-146 tone dialer, open the dialer and replace the crystal (the largest shiny metal component). The exact value needed is 6.502457409Mhz. Unfortunately, that crystal is not commonly manufactured. A crystal close to that value will create a tone that falls within tolerances. The most popular choice is the 6.5536Mhz crystal. When you are finished replacing the crystal, program the P1 button with five *'s. That will simulate a quarter tone each time you press P1.