ACTS is an acronym for Automated Coin Toll System. This is the system of in-band signalling used by telco-owned payphones in the United States and Canada to communicate billing information to a toll switch. ACTS uses a system of audible MF tones played through the line to tell the switch how many coins have been deposited, and in what denominations.
ACTS tones for the American telephone system:
Nickel: 1700 Hz + 2200 Hz played for 66 ms
Dime: 1700 Hz + 2200 Hz played twice for 66 ms, with 66 ms of silence between tones
Quarter: 1700 Hz + 2200 Hz played five times for 33 ms, with 33 ms of silence between tones
The red box is a device created to simulate ACTS tones, thus allowing unscrupulous individuals to scam free phone calls out of the telephone company. |