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Science & Tech.
Mahesh

25/10/23 06:48 AM IST

SIM Card

In News
  • In 2021, there were more than 14 billion cellular devices in the world even though there were only 7 billion people.
SIM Card
  • ‘SIM’ stands for ‘subscriber identification module’.
  • Specifically, it is an integrated circuit, or a microchip, that identifies the subscriber on a given network.
  • Imagine each cellular network is a city whose residents are identified by a number, called the international mobile subscriber identity (IMSI), and their locations by some data. The SIM card is a subscriber’s ID card in this city.
  • When someone wishes to contact a subscriber in this city, the network uses the subscriber’s SIM card to find them and confirm their identity.
  • In order for a mobile phone to connect to any cellular network that follows the Global System for Mobile Communications (GSM) standard, a SIM card is mandatory.
  • This relationship is established using a unique authentication key – a piece of data that a user needs to ‘unlock’ access to the network.
  • SIM cards also store information about its own ID number (the integrated circuit card identifier), the IMSI, the subscriber’s location area identity (i.e. their current location), a list of preferred networks (to whom the subscriber can connect when roaming), emergency numbers, and – depending on the space available – the subscriber’s contacts and SMS messages.
SIM card working
  • SIM cards are designed according to the ISO/IEC 7816 international standard maintained by – as its name indicates – the International Organisation for Standardisation and the International Electrotechnical Commission.
  • It applies to electronic identification cards, including smart cards.
  • In this standard, the card itself consists of the integrated circuit, which is glued to a silicon substrate on the top side.
  • On the other side of the substrate are metal contacts, which form the gold-coloured side of the SIM card.
  • Wires connect the integrated circuit from its bottom side to the metal contacts on the top side, and the contacts interface with the phone’s data connectors.
  • On the network side, the SIM helps a phone establish its place within a cellular network.
  • When a subscriber dials a recipient’s number, the phone sends data via the network – signed by the key on the SIM card – to a telephone exchange.
  • If the recipient is connected to the same exchange, the network establishes their identity and the call is routed to them.
  • If the recipient is ‘located’ elsewhere, a computer connected to the network routes the call there according to the most optimum route.
SIM card History
  • SIM cards are a type of smart card, and the history of smart cards begins in the late 1960s, when West German engineer Helmut Gröttrup reportedly first had the idea to stick an integrated circuit in a plastic panel the size of a credit card.
  • The size and architecture of this microchip evolved in leaps and bounds in the subsequent decades, following Moore’s law.
  • The SIM card itself evolved according to the standards that defined the networks to which its users wished to connect.
  • The European Telecommunications Standards Institute (ETSI) prepared the GSM Technical Specification 11.11 regarding the SIM card.
  • Until 2G networks, the term ‘SIM card’ denoted both the hardware and the corresponding software.
  • This changed with the advent of the Universal Mobile Telecommunications System with 3G networks, when ‘SIM’ became only the software; the hardware was called the Universal Integrated Circuit Card (UICC).
  • The software was also upgraded to an application called Universal SIM, or USIM, which could be modified to be compatible with the identification and security requirements of 3G, 4G, and 5G networks.
  • As a result, a UICC loaded with both SIM and USIM applications can work with networks of all generations.
eSIM
  • In the eSIM paradigm, the SIM software is loaded to a UICC that is permanently installed in the mobile equipment in the factory itself, i.e. it can’t be removed. (This is called the eUICC.)
  • Users using mobile equipment with this capability – such as the Google Pixels 2, 3, and 4 or the iPhone 14 series – don’t have to bother with physically replacing their SIM cards when they join or switch networks.
  • Instead, the network operator simply has to reprogram the eSIM, which can also be done remotely.
  • An eSIM has two immediate advantages.
  • First, it is considered to be environmentally friendlier than a physical SIM: its reprogrammability means no need for more plastic and metal for a new SIM.
  • Second, if a malicious person gains access to your phone, they won’t be able to separately access the SIM application nor be able to duplicate it.
  • There are also at least two disadvantages. First, in some countries, including the U.S., eSIMs can be programmed by subscribers themselves.
  • But this process might be difficult for those with low digital literacy, such as the elderly.
  • Second, an eSIM can in theory allow network operators to track subscribers’ data, including inside apps on the device and especially in the absence of data privacy laws.

Source- The Hindu

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