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" 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.
Read more about this topic: Green Box (phreaking)
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