Abstract: In an electronic coin telephone set, a fraud prevention arrangement prevents fraudulent coin tones originating at a telephone transmitter from being provided to a central office over a coin subscriber loop. The arrangement comprises a first and second transmission channel for alternately connecting the transmitter to the central office and also a fraud filter disposed in the second transmission channel. The fraud filter attenuates a selected frequency originating at the transmitter that is indicative of coin deposits. When coin deposits are not required by the central office, the transmitter is connected to the central office through the first transmission channel. When coin deposits are required by the central office, however, the arrangement connects the transmitter to the central office through the second transmission channel thereby avoiding the fraudulent generating of coin tones through the telephone transmitter.

Abstract: This invention pertains to a microcomputer controlled coin telephone set which prevents coin call fraud and performs all of the coin discrimination functions. The microcomputer also checks the operational readiness of the telephone set to prevent the acceptance of coins into a hopper for late collection by a coin box unless or until the set is fully functional.

Abstract: A microcomputer controlled coin telephone set prevents coin call fraud and also checks the operational readiness of the telephone set to prevent the acceptance of coins into a hopper for later collection by a coin box unless or until the set is fully functional. Capable of being interrogated remotely, a local memory is used for storing coin deposit information and generating coin deposit signals in order of deposit to a central office. In those instances where the line power drops below that necessary for full operation as a coin telephone, low power sensing circuits convert the telephone to the POTS mode which allows speech and dialing capabilities. Similarly, any type of chute failure, or a full hopper causes the telephone to revert to the POTS mode. While in the POTS mode, any coins deposited in the telephone are returned to the customer.