Red box (phreaking)
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. In the United States, a nickel is represented by one tone, a dime by two, and a quarter by a set of five. Any device capable of playing back recorded sounds can potentially be used as a red box. Commonly used devices include modified Radio Shack tone dialers, personal MP3 players, and audio-recording greeting cards.
History
The term "red box" to refer to a phreaking box dates to 1973 or earlier. Red box use became more widespread in the 1990s following the publication in 2600 Magazine of instructions on how to make a red box by replacing a crystal oscillator in a tone dialer. Red boxes grew obsolete in the 2000s as phone systems in the US and other nations updated their signaling technology.Technical details
United States
The tones are made by playing back 1700 Hz and 2200 Hz tones together. One 66 ms tone represents a nickel. A set of two 66 ms tones separated by 66 ms intervals represent a dime, and a quarter is represented by a set of five 33 ms tones with 33 ms pauses. A single 650 ms tone represents a dollar, but this is rarely used.The system that handles these tones is called the Automated Coin Toll Service, or ACTS. However, since ACTS has been phased out of service in much of the United States, combined with the integration of acoustic filters into many payphone handsets, the practice of red boxing is rarely possible any longer.