SIM :

• SIM stands for Subscriber Identity Module.
• SIM contains users subscription information and contacts of phonebook.
• SIM is protected by PIN or password.
• SIM is a smart card which has unique IMSI (International Mobile Subscriber Identity) number.
• It allows user to retain the information even after he changes his mobile.
• It contains 3 modules that is CSIM, USIM and ISIM where CSIM stands for CDMA(Code Divsion Multiple Access) Subscriber Identity Module, USIM stands for Universal Subscriber Identity Module, and ISIM stands for IP Multimedia Services Identity Module.