Called party fraud detection in an automated coin system

摘要

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.