Understanding the IMEI
The International Mobile Equipment Identity (IMEI) is a unique identifier crucial for validating a device's legitimacy. It is typically a 15 or 17-digit number that is securely stored, often under the battery. IMEI plays a significant role within the Global System for Mobile Communications (GSM), Wideband Code Division Multiple Access (WCDMA), and certain satellite devices for the purpose of identification.
It's important to note that the IMEI number is not tied to a specific subscriber and doesn't establish a permanent subscriber relationship. Even if you swap your SIM card (Security Information Management or SIM card), it won't prevent your phone from being banned because the IMEI number is intrinsic to the phone itself, stored internally and not on the SIM card.
IMEI numbers generally follow the format: AA-BBBBBB-CCCCCC-D, with each segment conveying specific information:
- AA: Represents the Reporting Body Identifier, signifying the Type Allocation Code (TAC) approved by the GSMA;
- BBBBBB: Represents the remaining TAC digits;
- CCCCCC: Represents the serial sequence of the model or mobile phone;
- D: Represents the algorithm used to validate the ID number, often a LUHN check digit for the entire model or simply 0.
The check digit, calculated using the LUHN formula, serves as the last digit in the IMEI and ensures accuracy in entries within the central equipment identity register (CEIR). Displaying the check digit electronically and in print, both on the label and packaging, is essential.
IMEI numbers also hold information about the manufacturer, model type, date, and country of approval, which can be identified in mobile phones with known IMEI numbers. The primary purpose of the IMEI number is to facilitate the blocking or tracking of lost mobile phones through the IMEI database (IMEI DB). This central database contains essential IMEI information and is utilized globally by millions of GSM and 3G devices in GSM networks. When a phone powers on, the IMEI number is transmitted and verified by the IMEI DB in the network's Equipment Identity Register (EIR).
For efficient utilization and access to IMEI information, the GSM Association provides IMEI DB member access to GSM and 3G operators worldwide. These operators rely on IMEI DB data to determine customer device types and supported features, enhancing network management and security.