Cellular Technical Services Company, Inc.

Evan R Green

David M Stanhope

Dmitry Kaplan

Randolph W McKernan

David N Hoogerwerf

Howard L Wilburn

Randy McKernan

William Gerrit Barrere

Wm 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 system for the authorization of wireless telephone communications establishes two sets of authorized telephone numbers. A first set of authorized telephone numbers are supplied by the customer, and the second set of authorized numbers are derived from customer bills paid by the customer. The system analyzes transmission characteristics from an unauthenticated cellular telephone and attempts to verify its authenticity based on the transmission characteristic by analyzing the transmission characteristic with respect to stored reference waveforms for the authentic wireless telephone. However, the results of this signature analysis if negative may be overridden if the telephone number dialed by the unauthenticated cellular telephone matches a telephone number in either the first or second sets of authorized telephone numbers. The system also includes a technique for modifying the reference waveforms to compensate for changes in the transmission characteristic. The system will only consider the inclusion of transmission characteristics from the present communication if the dialed digits for the present communication match one of the telephone numbers in either the first or second sets of authorized telephone numbers.

System and method for the verification of authentic telephone numbers in

A system and method for the detection of fraudulent use of a wireless telephone system includes a fingerprint analyzer that identifies an unauthenticated wireless telephone as authorized or fraudulent based on a fingerprint of the unauthenticated wireless telephone. The system maintains a valid destination list specific for each authorized wireless telephone. Each valid destination list contains destinations considered to be valid for that particular authorized wireless telephone. When an unauthenticated wireless telephone transmits a call request containing a destination, the system classifies the call as valid when the destination is in the valid destination list for the authorized wireless telephone regardless of whether the fingerprint analyzer identifies the unauthenticated wireless telephone as fraudulent. The system may bypass or terminate the fingerprint analysis, or simply ignore the result of the fingerprint analysis by the fingerprint analyzer. The system also maintains an invalid destination list specific for each authorized wireless telephone with destinations considered to be invalid for that particular authorized wireless telephone. Calls to such destinations are blocked. The system further maintains a suspicious destination list containing destinations considered to be potentially fraudulent. When the destination contained in the call request is in the suspicious destination list, the fingerprint analysis is performed with a higher threshold to require a closer match between a fingerprint of the unauthenticated wireless telephone and a stored fingerprint of the corresponding authorized wireless telephone.

Apparatus and method for preventing fraudulent calls in a wireless

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.

Automated forced call disruption for use with wireless telephone systems

A system and method extracts a portion of a transmitted waveform and compares the transmission characteristics of the extracted waveform to determine if they match a stored fingerprint associated with the transmitter, such as a cellular telephone. The system adaptively creates fingerprint data by storing a plurality of waveforms believed to be from a particular transmitter and calculates the variability of the individual transmissions with respect to a composite mean waveform of the transmission characteristics. The system emphasizes the variability between the individual waveforms and the composite mean waveform and determines variability values for each of the individual waveforms in the fingerprint. When the system receives an additional unidentified transmission purported to be from the transmitter with the stored fingerprint, the system determines whether the variability of the unidentified waveform fits within the predetermined margins of variability for the fingerprint. If the variability of the unidentified waveform is less than a predetermined variability threshold, the system considers the waveforms to be a suitable match. The system can adaptively include new waveforms in the fingerprint by determining whether the newly-received transmission characteristics meet a series of criteria for inclusion in the fingerprint. In addition, the system analyzes the newly-received waveform and all waveforms forming the fingerprint to determine if any of the waveforms exceed a predetermined maximum variability value. A waveform that exceeds the maximum variability value is eliminated from the fingerprint. The system is easily automated, thus providing a useful analysis technique for communications network such as cellular telephone systems where a large population of transmitters with similar transmission characteristics are operating at any given time.

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Bothell, WA, United States of America

Evan R Green