SIM is an abbreviation for Subscriber Identification Module. It is a chip with an embedded integrated circuit that is inserted in a mobile phone to act as the intelligent source for varied forms of network communication. Anybody who is an account holder with telephone service provider is their subscriber and each has a unique account.
Uses of Sim
SIM is a unit that has memory hence data storing capability, is utilized by both service provider and its account holder. It is the SIM that holds one’s account information which is unique to every subscriber. Similarly, the SIM’s service provides identify different accounts using the number stored in the SIM card.
SIM cards have some small memory usually between 16-64 kilobytes that stores subscriber’s telephone number used in making calls, sending and receiving messages together with other services provided.
Whenever one is roaming in foreign countries, foreign network providers use this network identity to determine their support for SIM.
Apart from keeping the phone number, it also stores network authorization data, a contacts list, some messages as well as one’s personal security keys. The key plus other authentication data is encrypted for security purpose.