SIM Cards

A Subscriber Identity Module (SIM) is part of a removable smart card ICC(Integrated Circuit Card), also known as SIM Cards, for mobile cellular telephony devices such as mobile computers and mobile phones. more...

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SIM cards securely store the service-subscriber key (IMSI) used to identify a GSM subscriber. The SIM card allows users to change phones by simply removing the SIM card from one mobile phone and inserting it into another mobile phone or broadband telephony device.

The use of SIM cards is mandatory in the GSM world. The equivalent of a SIM in UMTS is called the Universal Subscriber Identity Module (USIM), whereas the Removable User Identity Module (RUIM) is more popular in CDMA devices.

SIM cards are available in two standard sizes. The first is the size of a credit card (85.60 mm × 53.98 mm x 0.76 mm). The newer, more popular miniature-version has a width of 25 mm, a height of 15 mm, and a thickness of 0.76 mm.

The First SIM Card made in 1991, Munich smart card maker Giesecke & Devrient sold the first 300 SIM cards to Finnish wireless network operator Elisa Oyj (ex. Radiolinja).

W-SIM is a SIM card which also integrates core cellular technology into the card itself.

Computer Integration

The SIM card is optional depending on the type of WWAN (Mobile Broadband) card that is installed in a laptop, such as the Dell Latitude D830, or other capable device.

Operating systems

SIM operating systems come in two main types: Native and Java Card. Native SIMs are based on proprietary, vendor specific software whereas the Java Card SIMs are based on standards, particularly Java Card which is a subset of the Java programming language specifically targeted for small embedded devices. Java Card allows the SIM to contain programs that are hardware independent and interoperable.

Data

SIM cards store network specific information used to authenticate and identify subscribers on the Network, the most important of these are the ICCID, IMSI, Authentication Key (Ki), Local Area Identity (LAI) and Operator-Specific Emergency Number. The SIM also stores other carrier specific data such as the SMSC (Short Message Service Center) number, Service Provider Name (SPN), Service Dialing Numbers (SDN), Advice-Of-Charge parameters and Value Added Service (VAS) applications. (look to GSM 11.11)

ICCID

Each SIM is Internationally identified by its ICC-ID (Integrated Circuit Card ID). ICCIDs are stored in the SIM cards and are also engraved or printed on the SIM card body during a process called personalization.

Read more at Wikipedia.org