.:GSM Technical Terms

IMEI - International Mobile Equipment Identity

The IMEI (International Mobile Equipment Identity) is a unique 17 or 15 digit code used to identify an individual mobile station to a GSM or UMTS network

The Structure of an IMEI Number

IMEI numbers either come in a 17 digit or 15 digit sequences of numbers. The IMEI format currently utilized is AA-BBBBBB-CCCCCC-D:

• AA: These two digits are for the Reporting Body Identifier, indicating the GSMA approved group that allocated the TAC (Type Allocation Code).
• BBBBBB: The remainder of the TAC
• CCCCCC: Serial sequence of the Model
• D: Luhn check digit of the entire model or 0 (This is an algorithm that validates the ID number)

EFR - Enhanced Full Rate

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