SIM Full Form – Working & Overview

A SIM is purposely usable for making phone calls or sending messages. Also, the SIM cards store contact information of other subscribers.

Furthermore, these chips can work on GSM as well as CDMA mobile devices. Besides, Sim cards are integrated circuits embedded with semiconductors. They are usually made up of PVC coating and are transferrable from one device to another.

Moreover, it is used to identify and authenticate different subscribers worldwide.

Subscribers identification process makes through different communication telephony devices such as mobiles, satellite phones, watches, and computers.

SIM Full Form

The full form of SIM is Subscriber Identity Module or Subscriber Identification Module.

Below enlisted are the resources useful in authentication and communication across the world.

A SIM is a portable chip that is used to store the following data securely:

  • ICCID (Integrated Circuit Card Identifier) – a unique serial number
  • IMSI (International Mobile Subscriber Identity) Number
  • Authentication Key

ICCID Serial Number


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It is a type of unique serial number assigned to every sim card for their identification. ICCID number can be up to 20 digits long and varies according to different countries. Besides, this unique number helps identify physical sim cards as well as eSIM profiles.

IMSI Number


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Each Sim cards has it’s unique International Mobile Subscriber Identity number regarding particular operator or services. These unique numbers help in the identification of a specific subscriber of an operator.

All mobile operators use these IMSI numbers to connect phone calls and make communication. Also, it has a particular format.

  • MCC (Mobile Country Code) – the first three digits represent country code
  • MNC (Mobile Network Code) – the next two digits represents mobile network code
  • MSIN (Mobile Subscriber Identification Number) – These are ten-digit numbers which help in communicating with any particular user

Note: Digits numbers may vary according to different countries.

Authentication Key

The key holds a 128-bit value that helps in the authentication of SIMs on a particular mobile phone. Moreover, each sim holds the key that assigned while going down the process of personalization.

The network operator assigns the key, and also it is stored in the database of the network carrier. The key is the utmost aspect of any sim card.

Formats of SIM

  • Credit Card size sim: It was first invented and later small size SIMs came into development
  • Mini-SIM: As the full-size sim started to eliminate, Mini SIMs got a new face in the latest mobile phones
  • Micro SIM: It has the same thickness but got reduced in length and wideness
  • Nano SIM: It is the smallest sim currently in use of smartphones. The sim has a significant reduction in size, thickness, and length

So, these are the essential aspects one should know about sim cards, including SIM full form; it’s components and uses.

If there’s something left by us or you have any argument, please let us know in the comment box below.

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