A Subscriber Identity Module, better known as a SIM card, is a small portable memory chip used in mobile devices such as cell phones. The SIM card contains information specific to the user, such as text messages, phone numbers and pictures.
Definition
The SIM card is a smart card or an integrated circuit card (ICC), which is a pocket-sized memory card with embedded circuitry that can process data.
History
Smart card innovators Giesecke & Devrient, a German company, created the first SIM card in 1991 sending out 300 cards to a company in Finland called Elisa Oyj, that operated a wireless network.
Portability
SIM cards can be switched from one phone to another. The phone reads the data and the information is processed just as if the user were calling from her own personal phone.
International Use
Domestic users can keep all phone activity local to the area by purchasing a SIM card in their overseas location and inserting it into the phone. The phone will need to be unlocked, by inputting a code, for international usage.
Compatibility
SIM cards are not supported on the CDMA network. They can only be used on the GSM, Global System for Mobile Communication network.
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