SIM - or SIM Card

A SIM is the GSM chip that is used to insert into a phone to 'personalise' the handset. The handset would then work on that number and have access to all the information stored on a SIM. It enables a user to quickly change handsets without affecting the line or number that is used to make and recieve calls.

SIM stands for Subscriber Identity Module. It can also be called a smart card as it uses the same technolgy that other smart cards use.