chinger

A chinger is a telephone fraud device that mimics the frequency made by a pay telephone when money was dropped into it. Putting money in the coin slot caused a DTMF or Dual Tone Multi Frequency signal to be sent out to the central switching box which registered it and when enough money had been inserted into the phone would connect the call. The chinger could mimic that sound and thus produce the equivalent effect of dropping a quarter into the pay phone. So basically, a chinger allowed the user to make unlimited free calls from certain pay phones. They could be made using a simple pocket electronic address book sold at Radio Shack, and replacing the chip inside to alter the output sound. They were also known as "red boxes" but the name chinger probably referred to the chiming sound it made when mimicing a quarter drop. Most modern pay phones no longer use the DTMF tones, rendering the chinger obsolete... but it was fun while it lasted!