Red box

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For other uses, see Red box (disambiguation).

A red box is a phreaking device that generates tones to simulate inserting coins in pay phones, thus fooling the system into completing free calls. A dime is represented by two "dings", a nickel by one, and a quarter by a lower-pitched chime. Any device capable of playing back recorded sounds is a potential red box. Commonly used devices include modified Radio Shack tone dialers and Hallmark audio-recording greeting cards.

The specifications for the tones are as follows:

 RED BOX FREQS: 1700 Hz AND 2200 Hz MIXED TOGETHER

 A NICKEL IS 66 MS ON (1 BEEP).
 A DIME IS 66 ms ON, 66 ms OFF, 66 ms ON (2 BEEPS)
 A QUARTER IS 33 ms ON, 33 ms OFF REPEATED 5 TIMES.
 (MS= MILLISECOND).

In the United Kingdom:

 10p is 1000 Hz for 200 ms
 50p is 1000 Hz for 350 ms

Red boxes no longer work in most western nations - the pay phones either include filters on the handset to remove this sound, or in many cases, use digital systems that are not so easily fooled. The basic concept still works in many other countries, however.