Called party fraud detection in an automated coin system

In a telephone system wherein a calling coin station and a called station are interconnected in a trunk circuit intermediate a local office and a toll office, fraud detection and deposit apparatus, which comprises:

• switch means in the trunk circuit for splitting the interconnection into a first portion connected to the calling station and into a second portion connected to the called station,
• a network connected to each of said portions,
• first and second coin deposit tone detectors connected to said network,
• first control means during a coin deposit interval for controlling said network to establish a connection between said first portion and said first coin deposit tone detector and a connection between said second portion and said second coin deposit tone detector and for controlling said switch means to split the interconnection, and
• second control means connected to said first and second coin deposit tone detectors for counting the coins detected by said first coin deposit tone detector and for generating an alarm if coin tones are detected by said second coin deposit tone detector.

In a telephone system wherein a calling coin station and a called station are interconnected by a communication path therebetween, fraud detection and coin deposit detection apparatus, which comprises:

• isolation means connected in the communication path for providing a first path for conveying signals received from the calling station to the called station and a second path for conveying signals received from the called station to the calling station,
• a first coin tone detector connected to said first path for detecting coin deposit signals received over said first path,
• a second coin tone detector connected to said second path for detecting coin deposit signals received over said second path, and
• logic means responsive to said first and second coin tone detectors for generating a fraud indication if a coin deposit signal is detected by said second coin tone detector and not by said first coin tone detector.

In a telephone system wherein a calling coin station and a called station are interconnected in a trunk circuit intermediate a local office and a toll office, fraud detection and coin deposit detection apparatus, which comprises:

• switch means in the trunk circuit for splitting the interconnection into a first portion connected to the calling station and into a second portion connected to the called station,
• first and second hybrid circuits having first and second unidirectional paths therebetween,
• a network controllable to connect said first portion to said first hybrid circuit and to connect said second portion to said second hybrid circuit, said first unidirectional path conveying signals from said first portion received via said first hybrid circuit to said second hybrid circuit, and said second unidirectional path conveying signals from said second portion received via said second hybrid circuit to said first hybrid circuit,
• a first coin tone detector connected to said first unidirectional path and detecting coin deposit tones received thereover,
• a filter in said second unidirectional path for distorting coin deposit tones received thereover, a second coin tone detector connected to said second unidirectional path between said second hybrid circuit and said filter and detecting coin deposit tones received over said second unidirectional path, and
• logic means connected to said first and second coin tone detectors for generating a fraud indication if a coin tone is detected by said second coin tone detector and not by said first coin tone detector, and for generating a valid coin indication if a coin tone is detected by only said first coin detector or by both said first and second coin tone detectors.

In a telephone system wherein a calling coin station and a called station are interconnected by a communication path therebetween, fraud detection and coin deposit detection apparatus, which comprises:

• isolation means in the communication path for providing a first path indicating signals apparently directed from the calling station to the called station and for providing a second path indicating both the signals apparently directed from the calling station to the called station and signals apparently directed from the called station to the calling station,
• first coin detector means connected to said first path for generating a first coin present indication (CTD1) upon the detection of a coin deposit signal indicated over said first path,
• second coin detector means connected to said second path for generating a second coin present indication (CTD2) upon the detection of a coin deposit signal indicated over said second path,
• signal comparator means jointly responsive to said first and second coin detector means for generating a valid comparison signal (VCS) only if the strength of the detected coin deposit signals is within a predetermined range, and
• logic means responsive to said first and second detector means and to said signal comparator means for indicating a valid coin (V) has been detected where V = (CTD1) (VCS) + (CDT1) + (CTD2) and for indicating a fraudulent coin (F) has been detected where F = (CTD1)(VCS).

In a telephone system wherein a calling coin station and a called station communicate over a communication path therebetween, signals from the calling station generally traveling in a first direction over the communication path to the called station and signals from the called station generally traveling in a second opposite direction over the communication path to the calling station, the combination comprising:

• first coin detector means connected to said communication path to receive the signals traveling thereover in one direction for detecting a coin deposit signal,
• second coin detector means connected to said communication path to receive the signals traveling in both directions over said communication path for detecting a coin deposit signal,
• signal comparison means responsive to said first and second coin detector means for indicating whether or not the strength of detected coin deposit signals is within a predetermined range, and
• logic means jointly responsive to said first and second coin detector means and to said signal comparison means for indicating whether a detected coin deposit signal is a valid coin deposit signal from the calling station or a fraudulent coin deposit signal from the called station.

In a telephone system wherein a calling coin station and a called station are interconnected and communicate over this interconnection, at least a portion of the interconnection including a first unidirectional path conveying signals from the calling station to the called station and a second unidirectional path conveying signals from the called station to the calling station, the combination comprising:

• bridge circuitry connected to said first and second unidirectional paths for applying the signals received over both said paths to a combined path,
• first and second coin tone detectors respectively providing first (CTD1) and second (CTD2) coin tone present signals upon detection of a coin deposit signal,
• network means, during a coin deposit interval, for connecting said first unidirectional path to said first coin tone detector and for connecting said combined path to said second coin tone detector,
• signal comparator logic connected to said first and second coin tone detectors for providing a valid Comparison signal (VCS) if the signal strength of a detected coin deposit signal is within a predetermined range, and
• logic means responsive to said coin tone detectors and said signal comparator logic for providing a valid coin indication V where V = (CTD1)(VCS) + (CTD1)(CTD2) and for providing a fraudulent coin indication F where F = (CTD1)(VCS).

In a telephone system including a local switching office and another switching office interconnecting a calling and a called station,

• first detecting means for detecting coin deposit tones being conveyed over the interconnection from the calling station to the called station,
• second detecting means for detecting coin deposit tones being conveyed over the interconnection from the called station to calling station,
• logic means jointly responsive to said first and second detecting means for comparing the signal strengths of a detected coin deposit tone to determine if one of said detecting means detected a tone reflected back from one of the switching offices, and
• means jointly responsive to said first and second detecting means and to said comparing means for indicating whether the detected coin deposit tone is a valid coin deposit tone from the calling station or a fraudulent tone from the called station.