Green box (phreaking)
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In Phreaking, the Green box was a device whose function was to manipulate the coin collection mechanism of Payphones. It employed three of the MF (multi-frequency) tones used in the Blue box and could be viewed as a subset of that device.
[edit] Operation
There are three basic functions in a green box, and each one is activated with an MF tone. The green box's designers have noted that it is not possible to use the green box from the payphone being manipulated; it can only be used by the called party.
| Green Box MF frequencies | ||
| Function | Frequencies | MF Symbol |
|---|---|---|
| Coin Collect | 700 Hz + 1100 Hz | 2 |
| Coin Return | 1100 Hz + 1700 Hz | KP |
| Ringback | 700 Hz + 1700 Hz | 11/ST3 |
According to the text file "The Green Box"[1] by "The Blue Buccaneer" and "The Tracker", each of these frequencies should be sounded for at least 900 milliseconds. Each should also be preceded with a 2600 Hz "wink", or an MF "8" symbol (900 Hz + 1500 Hz), of about 90 ms in duration, followed by about 60 ms of silence. Most software green boxes emulate this rather than the MF symbols alone.
[edit] History
The green box was first proposed in the newsletter TAP in 1981 by Ted Vail and Nick Haflinger[2]. While others have written text files about this device, and numerous software tone generators exist which claim to emulate it, it is unknown if any physical devices were actually built (including by Vail and Haflinger). Despite this, any blue box could, with skillful timing on the part of its user, be used as a green box.
With the widespread phase-out of the ACTS signaling system, and indeed the long-completed phase-out of MF signaling in North America, the telephones for which this device was designed are no longer in service. Thus the green box can be considered obsolete.
[edit] Notes
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