SIM stands for Subscriber Identity Module, it is a 'smart card' or plastic that identifies the terminal. By inserting the SIM card into the terminal of all GSM phones, the user can have access to all the subscribed services. Without the SIM card, the terminal is not operational, except for dialling emergency numbers. It stores the identity of the phone and its owner, and allows access to a mobile GSM network. It can also store telephone numbers and addresses.
The SIM card is protected by a four-digit Personal Identification Number (PIN). In order to identify the subscriber to the network, the SIM card contains some parameters of the user, such as its, International Mobile Subscriber Identity (IMSI).
The SIM card should not be;
- Exposed to extreme elements - excessive heat
- Removed Unnecessarily
- Bent of scratched
- Incorrectly inserted
Any of the above will render the SIM Useless, it becomes JUNK.
Types of SIM card.