SIM: a subscriber identity module or subscriber identification module

A subscriber identity module or subscriber identification module mostly referred to as SIM Card is an integrated circuit chip that is intended to securely store the international mobile subscriber identity (IMSI) number and its related key, which are used to identify and authenticate subscribers on mobile telephony devices (such as mobile phones and computers). It is also possible to store contacts on many SIM cards. SIM cards are always used on GSM phones; for CDMA...