Backwards compatible, extended method to execute check number calculation of IMEI

• US 20010027117A1
• Filed: 02/15/2001
• Published: 10/04/2001
• Est. Priority Date: 02/17/2000
• Status: Active Grant

• Current Assignee: Nokia Mobile Phones UK Limited (Nokia Corporation)
• Original Assignee: Nokia Mobile Phones UK Limited (Nokia Corporation)
• Inventors: Alanara, Seppo
• Granted Patent: US 7,054,657 B2
• Time in Patent Office: Days
• US Class Current: 455/551
• CPC Class Codes: H04W 8/22 Processing or transfer of terminal data, e.g. status or physical capabilities
• CPC Class Codes: H04W 8/26 Network addressing or numbering for mobility support

Abstract

A method is taught to provide an improved mobile station International Mobile Equipment Identity (IMEI) code having at least a six digit hexadecimal SNR representation, in conjunction with modifying a Check Digit calculation procedure so as to insure backwards compatibility with an existing installed base of mobile stations having a six digit BCD SNR representation.

Claims

1. A mobile station comprising a memory device for storing an International Mobile Equipment Identity (IMEI) code having at least a six digit hexadecimal Serial Number (SNR) representation, wherein said SNR is used with a hexadecimal check digit calculation procedure so as to insure backwards compatibility with an existing installed base of mobile stations having a Binary Coded Decimal (BCD) SNR representation.

2. A mobile station as in

claim 1

, wherein the check digit calculating procedure is modified so that hexadecimal digits A, B, C, D, E and F are first converted to decimal digits 10, 11, 12, 13, 14 and 15, respectively, and then computing the check bit using an original check bit calculation algorithm (Luhn Algorithm).

3. A method as in

claim 1

, wherein the check digit calculating procedure uses base 16 for all calculations to derive a base 16 check digit.

4. A method for use with a mobile station of a type that stores a 14 digit International Mobile Equipment Identity (IMEI) code for generating a Check Digit (CD), comprising steps of

executing a preliminary step of encoding the 14 digit (D1, D2, D3, . . . , D14) IMEI in a hexadecimal representation;

then computing the CD by,

(A) doubling the values of the odd digits (D1, D3, D5, . . . , D13) of the IMEI using the hexadecimal number base;

(B) adding together the individual digits of the seven numbers obtained in Step A, and adding this sum to the sum of all of the even labeled digits (D2, D4, D6, D14) of the IMEI using the hexadecimal number base; and

(C) if the number obtained at the end of Step B ends in zero (0), setting the CD to zero (0), else if the number obtained at the end of Step B does not end in zero (0), setting the CD to be the difference between that number subtracted from the next highest hexadecimal number which does end in zero (0).

5. A method for use by a wireless communication system that includes a network and a plurality of mobile stations that each store a 14 digit International Mobile Equipment Identity (IMEI) code, the method generating a Check Digit (CD) and comprising steps of:

for a first type of mobile stations, executing a preliminary step of encoding the 14 digit (D1, D2, D3, . . . , D14) IMEI in a binary coded decimal (BCD) representation;

for a second type of mobile stations, executing a preliminary step of encoding the 14 digit (D1, D2, D3, . . . , D14) IMEI in a hexadecimal representation,

then computing the CD in the network, regardless of whether an IMEI is received from the first type of mobile station or from the second type of mobile station, by performing the steps of,

(A) doubling the values of the odd digits (D1, D3, D5, . . . D13) of the IMEI using the hexadecimal number base;

(B) adding together the individual digits of the seven numbers obtained in Step A, and adding this sum to the sum of all of the even labeled digits (D2, D4, D6, . . . , D14) of the IMEI using the hexadecimal number base; and

(C) if the number obtained at the end of Step B ends in zero (0), setting the CD to zero (0), else if the number obtained at the end of Step B does not end in zero (0), setting the CD to be the difference between that number subtracted from the next highest hexadecimal number which does end in zero (0).