Cellular Technical Services Company, Inc.

David N Hoogerwerf

David M Stanhope

Evan R Green

Randy McKernan

Randolph W McKernan

William Gerrit Barrere

A method and system for actively and rapidly collecting reference waveforms from a large number of cellular telephones is provided. The reference waveforms are used to generate fingerprints which are used to distinguish between authorized cellular telephones and unauthorized cellular telephones. Initially, the system selects a cellular telephone whose reference waveform is desired. The selected cellular telephone is then sent a polling message such as a page or registration request. The cellular telephone receives the polling message and transmits a radio frequency (RF) signal containing a reference waveform that contains certain transmission characteristics unique to the selected cellular telephone. From the received RF signal, the reference waveform is extracted and stored. Preferably, the selected cellular telephone is polled repeatedly in order to receive a sufficiently large number of reference waveforms to be able to generate an accurate fingerprint. One method of polling the cellular telephone is by calling the selected cellular telephone through a cellular telephone system. Another method of polling the cellular telephone is by transmitting a control message such as a page, registration, audit or maintenance message.

Active waveform collection for use in transmitter identification

A method and system for detecting a voice channel grab by a pirate in a cellular telephone network. Initially, RF signals transmitted to and from an authorized cellular telephone over the control and voice channels are monitored to track call processing activities and obtain various data that are used to detect potential voice channel grabbing attempts. The data may include such things as RSSI, change power output messages and responses, and hook-flash signal. From the data, the system looks for two events. A first event is an unexpected change or an absence of an expected change in the voice channel RF signal indicating that the pirate may be transmitting on the voice channel. The first event may be any one or more of the following: (1) a sudden upward shift in the voice channel RSSI; (2) an unexpected phase shift of either the RF signal or the SAT signal contained in the RF signal; and (3) an absence of an expected shift in the RSSI that corresponds to the change power level message from the network. The second event is receipt of a message indicative of a request to establish a new telephone connection such as a hook-flash message initiating a call conference. When the unexpected change in the RF signal and the message indicative of the request to establish the new telephone connection are detected, the system determines that the voice channel assigned to the authorized cellular telephone has been grabbed by the pirate. When the system determines that the channel grab has occurred, it prevents the pirate from establishing the new telephone connection by preventing receipt of dialed digits or terminating the connection on the voice channel.

Detection and prevention of channel grabbing in a wireless

A system and method for collecting fingerprint reference wave forms under controlled conditions includes a radio frequency (RF) enclosure designed to receive a cellular telephone. A control system, including a transmitter and receiver provides RF communications with a cellular phone placed in the enclosure. A processor controls operation of the transmitter and receiver. The processor sends commands to the cellular phone in the enclosure using the transmitter. The transmitted commands are selected to elicit a RF transmission from the cellular phone in response to the command. The receiver detects the response from the cellular telephone and generates a reference wave form indicative of the transmission characteristics of the transmitter of the cellular phone in the enclosure. The processor captures one or more reference waveforms that can be used to generate a fingerprint indicative of a transmission characteristic of the transmitter of the cellular telephone. In addition, the system can include an external power supply and temperature control system to vary the voltage level of power supplied to the cellular telephone in the enclosure and to vary the temperature in the enclosure. By varying the operating voltage and temperature, the processor can collect reference waveforms under a variety of operating conditions. In addition, the processor can select the carrier frequency for the cellular telephone and for the transmitter and receiver of the control system. Furthermore, the processor can vary the transmit power of the system transmitter and the transmit power of the transmitter within the cellular telephone itself. The system is sized to be readily moved from one location to another to permit the simple collection of reference waveforms under a variety of controlled conditions.

System and method for collection of transmission characteristics

A method and apparatus which provide the ability to disrupt normal completion of a specific call made through a wireless telephone system. The specified call can be forced to be immediately ended, re-routed immediately to a selectable destination, or linked to a local voice frequency interface. The disruption of the call can occur at any point in time over the duration of the call. The decision to disrupt the call, as well as which action to take against the call, can be selected manually by a human or automatically through a standard data interface provided. The call disruption apparatus can be interfaced to the wireless system through a circuit physically connected to the wireless telephone system equipment, or through a modulated radio frequency interface.

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Everett, WA, United States of America

David N Hoogerwerf