SIM full form: What is the full form of SIM?


First thing first, what is the full form of SIM? SIM full form is Subscriber Identity Module or Subscriber Identification Module.

What is a SIM?

SIM or Subscriber Identity Module is a circuit that stores the International Mobile Subscriber Identity (IMSI). It is a tiny memory chip that allows you to make calls across the world where the network is available. SIM is mainly used in mobile phones that work on the GSM network. SIM cards are easy to use, and you can utilize them with any phone that supports them.

Different types of data a SIM card stores

A SIM card might be tiny, but it stores a large number of essential data. Here is a list of data a SIM card can store.

  • Telephone numbers
  • Address book
  • Organization approval information
  • Messages
  • Individual Security Keys

A SIM card also contains an ICCID number, International mobile subscriber identity (IMSI), security and encoding data, and much more.

Size of a SIM card

When a SIM card was invented, it was the size of a Visa. SIM card of the size 15mm by 12mm. With time, now a SIM card comes in different sizes: Standard, Macro, and Nano.

History of SIM card

SIM card was first made by Munich keen card creator Giesecke and Devrient in the year 1991. Since it was made in Munich, it was first indicated by the European Telecommunication Standards Institute.


CDMA is another network available for mobile communication and is similar to GSM. Since there is no SIM in CDMA, it is not used much. In simple words, all the information is stored in the device networks. It makes it difficult for the user who wants to change the phone but not their service provider.


You need to know that a SIM can have many IMSIs. A roaming SIM is an example of many IMSI SIM cards. Based on the location you are in, the specific IMSI gets active. Apart from IMSI, ICCID is another unique identifier for the module. A standard network provider allocates the ICCID number, and the same is printed on the SIM card.


A SIM card is just a chip without an identity. Mobile providers allocate IMSI, and each mobile provider has a wide range of IMSIs. They also have authentication keys that are different for each sim store. These keys are used at the time of SIM registration and call setup.


SIM full form is Subscriber Identity Module or Subscriber Identification Module. SIM is a tiny chip present in the mobile phone and is connected to a particular phone network. There are many mobile network providers. I hope this blog helped you understand the full form of SIM.

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