Paying the initial rate in order to use a red box (on certain fortresses) left a sour taste in many red boxers mouths, thus the green box was invented. The green box generates useful tones such as COIN COLLECT, COIN RETURN, AND RINGBACK.
These are the tones that ACTS or the TSPS operator would send to the CO when appropriate. Unfortunately, the green box cannot be used at the fortress station but must be used by the CALLED party.
Here are the tones:
COIN COLLECT 700+1100hz
COIN RETURN 1100+1700hz
Before the called party sends any of these tones, an operator realease signal should be sent to alert the MF detectors at the CO. This can be done by sending 900hz + 1500hz or a single 2600 wink (90 ms.) Also do not forget that the initial rate is collected shortly before the 3 minute period is up.
Incidentally, once the above MF tones for collecting and returning coins reach the CO, they are converted into an appropriate DC pulse (-130 volts for return and +130 for collect). This pulse is then sent down the tip to the fortress. This causes the coin relay to either return or collect the coins.
The alledged "T-network" takes advantage of this information. When a pulse for coin collect (+130 VDC) is sent down the line, it must be grounded somewhere. This is usually the yellow or black wire. Thus, if the wires are exposed, these wires can be cut to prevent the pulse from being grounded.
When the three minute initial period is almost up, make sure that the black and yellow wires are severed, then hang up, wait about 15 seconds in case of a second pulse, reconnect the wires, pick up the phone, and if all goes well, it should be "JACKPOT" time.