SIM - Subscriber Identity Module
A Subscriber Identity Module card is a portable memory chip, that enables you to make phone calls from any corner of the Globe, where you get the subscriber's Network. It is used mostly in cell phones that operate on GSM network. A SIM card can easily be removed from one mobile phone and used in any other compatible phone.
A SIM Card can be used to hold & provide the following information :-
- Phone number
- address book
- network authorization data
- text messages
- personal security keys
- other data
How is it different from CDMA SIM
Phones that operate on the CDMA network most often, do not use SIM cards. Instead, they save any information in the handset itself. While this can be less convenient for users.