A Subscriber Identity Module or Subscriber Identification Module (SIM) is an integrated circuit chip that is intended to securely store the International Mobile Subscriber Identity (IMSI) number and its related key.
The SIM circuit is part of the function of a Universal Integrated Circuit Card (UICC) physical smart card, which is usually made of PVC with embedded contacts and semiconductors. “SIM cards” are designed to be transferable between di erent mobile devices. The development of physically smaller mobile devices has prompted the development of smaller SIM cards, where the size of the plastic carrier is reduced while keeping electrical contacts the same.
A SIM card contains its unique serial number (ICCID), international mobile subscriber identity (IMSI) number, security authentication and ciphering information, temporary information related to the local network, a list of the services the user has access to, and two passwords: a personal identification number (PIN) for ordinary use, and a personal unblocking code (PUK) for PIN unlocking.