What Identifies a SIM Card If the Card Is Used?

A Subscriber Identity Module (SIM) is a smart card that stores personal information to connect a mobile device to a specific network or carrier. It contains crucial information like phone numbers, user identity, locations, security verification keys, and contacts. 

SIM cards usually work through two different technologies: Global System for Mobile Communication (GSM) and Code Division Multiple Access (CDMA). The former is more prevalent among network providers. 

But how do these technologies help SIMs communicate and identify other SIM cards? Let's find out. 

What Are ICCID Numbers? 

ICCID stands for Integrated Circuit Card Identification. It is a unique identifier number for chip cards, including credit cards, national identification cards, and SIM cards. The ICCID number is stored within a SIM card's memory and inscribed on it. It helps SIMs identify devices when connecting to networks or when updating or retrieving information. 

The structure of the ICCID number has a combination of identifiers that include the following:

  • MII – It is the major industry identifier and consists of the first two digits of your SIM code. The telecommunication industry or SIM card codes always have 89 at the beginning. 
  • CC – It is the country code. The country code for Australia is 61. 
  • IIIN – It is the issuer identifier number, i.e., the code for the mobile operator you use. The IIIN cannot exceed two digits. It is also called the Mobile Network Code (MNC). However, the MNC and the operator code do not necessarily have the same value. 
  • IAIN – It is the individual account identification number. Apart from the checksum, the other numbers in ICCID are unique identifiers. The job of the IAIN is to distinguish IoT SIM cards from the rest, which means you can remotely activate and find your SIM worldwide. 
  • C – It stands for the checksum, which validates the integrity and completeness of the ICCID number. The Luhn algorithm helps to calculate the checksum using the other digits post-transmission. 

identify a sim card

What Other Identification Numbers Are There? 

The ICCID number can easily be confused with IMSI or IMEI numbers. However, all of these numbers are very different from each other, both in use cases and formation. 

For instance, the ICCID number is a SIM card identifier. It’s a unique code assigned to your SIM. The IMSI number is used to identify the SIM card user, and the IMEI is the device identifier. Let’s look at the latter two in more detail.  


The International Mobile Subscriber Identity (IMSI) number is a unique code that authenticates and identifies subscribers when they connect to a network. 

It has three major divisions:

    • MCC (Mobile Country Code)
    • MNC (Mobile Network Code)
    • MSIN (Mobile Subscriber Identification Number).


Every device has a 15-digit International Mobile Equipment Identity (IMEI) code, which uniquely identifies your phone. You can use this number to check information about your device, such as its brand, model, OS, etc.

Device manufacturers and phone carriers share IMEI numbers to track mobile phones that may be compromised or stolen.

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