A globally unique serial number assigned to every SIM card. While the IMSI identifies the subscriber within a mobile network, the ICCID identifies the physical SIM card itself. This distinction makes the ICCID essential for inventory management, provisioning, and ensuring the right card is associated with the correct user account.
An ICCID can contain up to 22 digits, although most are 19 or 20 digits. These digits follow an international numbering standard defined by the ITU (International Telecommunication Union) and ISO/IEC. They are typically printed directly on the SIM card and are also embedded in its memory, allowing mobile devices and operators to read them electronically.
Structure of the ICCID
- Issuer Identification Number (IIN): The first digits, including the industry identifier (89 for telecommunications) and country code, show who issued the SIM.
- Individual Account Identification: A unique sequence of digits that ties the SIM to a specific subscriber account.
- Check Digit: The final number, calculated using the Luhn algorithm, helps verify the accuracy of the ICCID.
Examples of ICCIDs
- A SIM issued in the United States might begin with 8901, followed by codes that identify the mobile operator and the subscriber account.
- A SIM from the United Kingdom typically starts with 8944, indicating its country of origin before narrowing down to the operator and card number.
The ICCID plays a central role in SIM lifecycle management. Carriers use it to activate or deactivate cards, transfer subscribers between devices, and track SIMs for fraud prevention and compliance. For end users, the ICCID usually remains behind the scenes, but it is a foundational element of mobile network operations.
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