Abstract: A system is disclosed for serving coin telephone calls on a wholly automatic basis without any operator intervention normally being required either for notifying the calling party of the required deposits or for monitoring the collection of coins deposited in the coin station. Moreover, coin tone detectors and announcement circuits are isolated so that coin deposits can be detected during announcements.

Abstract: This invention pertains to systems servicing coin operated telephones and, more specifically, to apparatus in such systems for preventing called party fraud in simulating coin deposit signals. During intermediate coin deposit periods, the network connection between the calling and called stations is split into calling and called portions and then these portions are extended and reconnected. A filter is inserted in the extended called station portion to attenuate fraudulent coin deposit signals originating from the called station. A coin tone detector connected to the extended calling station portion is still actuated by valid coin deposit signals from the calling station, but does not detect the attenuated fraudulent signals.