System for securing mobile telephones from unauthorized transmission

• US 5,337,345 A
• Filed: 07/29/1992
• Issued: 08/09/1994
• Est. Priority Date: 07/29/1992
• Status: Expired due to Term

• Current Assignee: Novatel Wireless Solutions (Inseego Corp.)
• Original Assignee: Novatel Communications Incorporated
• Inventors: Rooney, James, Cassidy, Barrie, McNab, David
• Primary Examiner(s): Chin, Stephen
• Assistant Examiner(s): Shankar, Vijay
• Application Number:
  US07/921,557
• Time in Patent Office: 741 Days
• Field of Search: 379/58, 379/59, 379/62, 379/63, 379/96, 379/95, 455/33.1, 455/54.2, 455/89, 455/95
• US Class Current: 455/410
• CPC Class Codes: H04W 12/08 Access security
• CPC Class Codes: H04W 76/10 Connection setup
• CPC Class Codes: H04W 88/02 Terminal devices

Abstract

A mobile telephone incorporating the invention includes in its transmitter circuitry a system for preventing unauthorized calls from being transmitted by the telephone. The system ensures that the telephone transmit only service and call requests that include the electronic serial number ("ESN") which is permanently stored in the telephone by the manufacturer, in an unalterable ESN memory. The system in one embodiment includes ESN detection circuitry which determines the bit position of an ESN in a service or call request and either compares the ESN in the request with the ESN stored in the ESN memory and transmit only requests that contain matching ESNs, or substitutes the ESN from the ESN memory directly into the requests as they are being transmitted. In an alternative embodiment, the system formats the requests using the ESN from the ESN memory and message information supplied to it by the user. The system, which is otherwise inaccessible to user-supplied information, then transmits the formatted requests.

Claims

1. A data transmitting system for use with a mobile telephone which is assigned an electronic serial number, the system including:

A. a processor for formatting a message for transmission, the processor including in the message an electronic serial number;

B. a data transmitter for transmitting the message;

C. an electronic serial number detector for determining the location of the electronic serial number in the message;

D. comparing means for comparing the electronic serial number in the message with the electronic serial number assigned to the telephone; and

E. means for disabling the data transmitting system if the comparing means determines that the electronic serial number in the message does not match the electronic serial number assigned to the telephone.

2. The data transmitting system of claim 1, wherein the system further includes an encoder for encoding the message as the message is being transmitted to include in the message clock information.

3. A data transmitting system for use with a mobile telephone which is assigned an electronic serial number, the system including:

A. a one-time programmable electronic serial number memory for storing the electronic serial number memory;

B. a processor for formatting a message for transmission, the processor including in the message the electronic serial number from the electronic serial number memory;

C. a data transmitter for transmitting the message;

D. an electronic serial number detector for determining the location of the electronic serial number in the message; and

E. means for replacing the electronic serial number in the message with the electronic serial number in the electronic serial number memory.

4. The data transmitting system of claim 3, wherein the system further includes an encoder for encoding the message as the message is being transmitted to include in the message clock information.

5. A data transmitter for a mobile telephone, the data transmitter including:

A. an electronic serial number memory for storing an electronic serial number assigned to the mobile telephone;

B. a message memory for storing a message and message related information;

C. means for retrieving the message and message related information from the message memory;

D. means for retrieving the electronic serial number from the electronic serial number memory;

E. formatting and encoding means for (i) formatting the message and including in the message the electronic serial number retrieved from the electronic serial number memory and (ii) encoding the message for transmission;

F. means for transmitting the encoded message.

6. A data transmitting system for use with a mobile telephone, the system including:

A. a controller for receiving message information and formatting the message information for transmission;

B. a one-time programmable electronic serial number memory which is accessible under the control of the controller;

C. the controller formatting the message for transmission and including in the formatted message the electronic serial number from the electronic serial number memory;

D. a data memory which is accessible under the control of the controller for storing the formatted message;

E. a data transmitter operating under the control of the controller for retrieving the formatted message from the memory and encoding and transmitting the formatted message.

7. A method of operating a mobile telephone, the method including the steps of:

A. formulating a service request which includes an electronic serial number;

B. transmitting the service request;

C. examining the request as it is being transmitted and determining the bit-position of the electronic serial number;

D. comparing the electronic serial number in the request with an electronic serial number assigned to the telephone at manufacture;

E. if the serial numbers are the same continuing to transmit the request; and

F. if the serial numbers are not the same ending the transmission.

8. The method of claim 7, wherein the method further includes:

i. in the step of examining the request as it is being transmitted, decoding the request to remove clocking information before examining the request; and

ii. in the step of continuing the transmission, encoding the request to add clocking information.

9. A method of operating a mobile telephone comprising the steps of:

A. formulating a service request which includes an electronic serial number;

B. transmitting the service request;

C. examining the request as it is being transmitted and determining the bit-position of the electronic serial number;

D. eliminating the electronic serial number in the request and inserting in the request an electronic serial number assigned to the telephone at manufacture.

10. The method of claim 9, wherein the method further includes:

i. in the step of examining the request as it is being transmitted, decoding the request to remove clocking information before examining the request; and

ii. in the step of continuing the transmission, encoding the request to add clocking information.