Coin Zone

Coin Zone was a semi-automated method of processing coin calls, typically calls to "zones" requiring more than the initial deposit, in many parts of New England through the mid-1970s.

Background

Coin Zone was used primarily in metropolitan areas with complex multi-zone charging schemes that required more than the initial deposit for certain calls. Coin Zone extended this multi-zone charging scheme to coin phones. Occasionally, Coin Zone was also used for short-haul long-distance calls, as in Allentown, Pennsylvania, where calls to Philadelphia and New York were handled through Coin Zone.

Unlike TSP and TSPS, Coin Zone calls were processed through traditional cordboards. Coin Zone operators did not know what number was being called. Instead, cordboard jacks were labeled with the amount required for the call to complete. Operators would manually supervise the correct deposit and then release their positions to allow calls to go through. As such, Coin Zone is not true operator-assisted dialing, but merely a semi-automated way of completing toll calls from coin phones that allowed the caller to direct-dial the number, saving valuable operator time.

For most of Coin Zone's operation, the initial deposit remained in the phone when the call went to the operator. Operators thus requested an additional deposit, the amount for the call less the initial deposit. In later versions of Coin Zone, with dial-tone first phones, the initial deposit was returned and then the entire deposit was requested.

Coin Zone was used only for a short period of time in the early 1970s. It was used in Long Island, New York, through 1974, when it was replaced by Traffic Service Position (TSP), which was first introduced in 1967. For a brief period of time, an automated version of Coin Zone was used from 1978 to 1986 by New York Telephone on ESS. Coin Zone was eventually rendered completely obsolete in the late 1970s by the Automated Coin Toll System (ACTS), which did not require an operator to manually supervise deposits from single-slot coin phones.

Security Vulnerabilities

Coin Zone operators would release calls for completion simply by pulling their cords, typically done when a caller had deposited the required amount. If the caller had not hung up, the call would then complete. Consequently, this allowed for the possibility of free calls by social engineering the operator, as callers who could trick the operator into hanging up first without having deposited the required amount would be able to have their calls go through for free. This was typically done by the caller pretending he did not have sufficient change and pretending to hang up. Other methods including pretending to be a lineman testing the coin phone operations, or pretending to be another Coin Zone operator. This was effective since if multiple operators plugged into a call at the same time, one might hear the other requesting the amount and release.