Bell Telephone Laboratories

Barry William Rogers

Edward Myron Prell

This invention relates to coin-operated telephones and apparatus for preventing the accidental or fraudulent simulation of coin deposit signals. At the beginning of each coin call or overtime period, a coding algorithm is randomly chosen at the coin station and the identity of the chosen algorithm is transmitted over the telephone line to a receiving telephone office. For each coin deposited, the coin station generates accumulated coin deposit information, codes it in accordance with the chosen algorithm and then transmits the coded accumulated deposit information to the telephone office. The office decodes the received information in accordance with the chosen algorithm identity information previously received at the telephone office to ascertain the amount deposited at the coin station.

Coin telephone antifraud system

This invention pertains to systems servicing coin operated telephones and, more specifically, to apparatus in such systems for detecting when called parties fraudulently generate coin deposit tones to simulate the coin deposit tones which should be received from a calling coin station. During intermediate coin deposit intervals, the network connection between the calling and called stations is split. A first coin tone detector is connected to the calling station portion while a second coin tone detector is connected to the called station portion. Logic is responsive to the detection of coin tones by these detectors for indicating whether a detected coin tone is valid or fraudulent.

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Geneva, IL, United States of America

Barry William Rogers