Arrangement for frustrating fraudulent telephone calls

For use in a telephone system wherein called address information is transmitted between originating and destination switching offices using tone signaling differing from signals generated by calling customer stations,

• a fraud device for originating toll free calls from a customer station by simulating said switching office tone signaling to manipulate switching equipment at said destination switching office,
• means for monitoring tones emanating from said fraud device, and
• means for blocking the completion of a call originating from said fraud device
• characterized by
• means for transmitting to said destination office discrete tones along with said monitored tones to cause a fraudulent call to be misdirected from its intended destination.

In a telephone system wherein called address signals generated by a calling station are automatically converted by a near-end office into corresponding switching signals for directing a far-end office to establish a connection to a first called line identified by said address signals and wherein

• a fraud device is controlled at said calling station for generating a second set of switching signals for transmittal to said far-end office in order to direct a connection to a second called line,
• means for blocking the establishment of said connection to said second line
• characterized by
• means for altering the switching signals transmitted from said fraud device to said far-end office to direct the call to a third line.

In a telephone system wherein each customer station is identified by an address comprising a corresponding ordered sequence of digits,

• wherein the digit sequence corresponding to a first called station address is transmitted from a calling switching office to a called switching office by a first ordered sequence of switching signals generated by the calling office in response to dialing signals generated by a calling station,
• wherein a calling station can avoid calling office toll charges by utilizing a fraud device to generate for direct transmission to said called office a second ordered sequence of switching signals representing a second called station, and
• wherein means is provided for detecting the usage of said fraud device,
• a method of frustrating a fraud call originated by said fraud device and addressed to said second called station comprising the steps of
• monitoring the ordered sequence of switching signals generated by said fraud device, and
• transmitting to said called office a new ordered sequence of switching signals other than said monitored sequence.