Subscriber identity module sim card is an IC ( Integrated circuit ) chip inside the Cellular device that stores Subscriber (Consumers) IMSI (International mobile subscriber identity), authentication key(Ki), ICCID and some carrier specific information such as Short Message Service Centre number (SMSC), service provider number (SPN), added service (VAS) and some other information.
This information is used for the purpose of identification and authentication of the subscriber on mobile devices. It tells the network service provider that which phone and number you are using and what the services currently being active on your phone. That’s the most important component of any Cellular device because without it smartphone is nothing but a multimedia box.
Types of SIM card
Mainly Two types of SIM card Technology currently is in use and that is
GSM stands for Global Standard for Mobiles which is mainly used in Europe, Africa, South America and some parts of Asia. It mainly usage the circuit switch system that split the 200 kHz signal into 8*25kHz signals. the It is developed by European telecommunications standard Institute and came in existence in Finland in December 1991.
CDMA stands for code division multiple access which is mainly used in the USA and some part of China. It is working on straight spectrum Technology and a special coding scheme.
Different size of a SIM card
The first sim card came in existence in 1991 from then to till now the different format of SIM card had been introduced. And these format of Sim Card has been made smaller over the years. Let’s have a look at the different formats of the SIM card.
1). Full size (1st Form Factor or 1FF): – 85.6 mm * 53.98 mm in size, look like a credit card size released in 1991
2). Mini sim(2FF or 2nd Form Factor): – 25 mm* 15 mm in size, released in 1996
3). Micro Sim (3FF or 3rd Form Factor): – 15 mm* 12 mm in size, released in 2003
4). Nano Sim (4FF or 4th Form Factor): – 12.3 mm* 8.8 mm in size, released in 2012
5). Embedded Sim(eSIM): – 6 mm* 5 mm in size
The size of the SIM card becomes smaller in size over time because as the size and thickness of the smartphone reduce, the question for space for other component is realized. So, make a compact design of cellular devices, the size of the SIM card reduced.
Out of all these, embedded SIM is not a traditional Sim because instead of a physical sim card, eSim is built right into your phone.
Data stored by the SIM card
It Store ICCID, IMSI number of the subscriber, security authentication and ciphering information, a piece of information about the different type of services that a user has access to, personal identification number and personal unblocking code(PUC).
1). International mobile subscriber identity (IMSI)
It is a very unique number for every user. It is usually as 15 digits but can be shorter. The first three digits represent the mobile country code that is MCC then second 3 digit represent mobile network code that is MNC. The remaining digits are the mobile subscription identification number (MSIN).
2). Integrated circuit card identifier (ICCID)
It is a 19 digit long number that includes the identification number of Issuer, individual account identification, and check digit, etc.
The memory size of the IC chip
Whenever you buy a sim card, The data capacity of the card is written on it. Older SIM cards usually come with 16 KB to 32 KB of non-volatile memory. But, the Newer card usually has 64, 128, 256, or 512 KB of size.
The first 16 to 32 KB is mostly used for address book and SMS storage. And remaining size is used for everything else related to network access subscriber identity, SMSC addresses, various preferred network list, and value-added services information.
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