International Mobile Equipment Identity – Wikipedia

The International Mobile Station Equipment Identity (IMEI) is a 15-digit serial number that is used to uniquely identify each GSM or UMTS terminal device worldwide.

IMEIs of devices approved from April 1, 2004 consist of three parts:

• The first eight digits form the TAC (Type Allocation Code). The first two digits of the TAC consist of a Reporting Body Identifier (RBI) and refer to the approving accreditation body. The remaining six digits contain the approval code. The TAC is unique for different terminal device hardware and can be used to identify a terminal device type.
• The next six digits form the actual serial number of the terminal device (SNR).
• The last digit is the check digit (CD). In GSM phase 1 devices it is ‘0’, from phase 2 it is assigned. The check digit is only stored in the device; a ‘0’ is always transmitted during network transmission. The algorithm for calculation is documented in 3GPP TS 23.003, Annex B.
  Until 2002, the TAC had only six digits and provided information about the manufacturer. This was followed by a two-digit Final Assembly Code (FAC) with a further manufacturer-specific identifier. During the transition period from January 2003 to the end of March 2004, two zeros were used instead. Both digits have been part of the TAC since April 2004.

GC Wizard offers the following check digit tools for EAN