Make it Secure

With the help of a phone’s serial number (also called the IMEI number–International Mobile Equipment Identity), the network operator can track the phone and switch its services off if it is stolen or lost. IMEI is a unique 15-digit code that identifies your handset to the service provider. You can look up your IMEI code by typing *#06# on you keypad. 

The four-digit phone lock code restricts answering to all incoming calls and allows you to make only emergency calls. This is factory set to 0000. You can change it to your own code.

The PIN (Personal Identification Number, also called the PIN1, depending on your handset) protects the SIM against unauthorized use and allows access to various other phone features. When enabled, you need to enter it each time the phone is switched on. If entered incorrectly three times in succession, the handset locks itself. To reactivate the handset in such a case you have to use the eight-digit PUK (Personal Unblocking Key) provided by the service provider. Further, if the PUK is entered incorrectly 10 times in succession, your SIM gets deactivated completely. You cannot change the PUK yourself.

The PIN2 is supplied by some SIM cards only and is required to access specific functions, like call cost counters, barred dial, call charge metering and fixed dial store. Similar to the PIN, the PIN2 gets deactivated if entered incorrectly three times in succession. An eight-digit PUK2 number provided by the service provider is used to reactivate it. The PUK2, if entered incorrectly 10 times in succession, renders the SIM useless.

Last but not the least, the key guard function prevents keys on the keypad from being pressed accidentally. Only an emergency call is allowed in this case. This acts as a keypad lock and uses a key combination to unlock.

Please note that some of these features may be specific to certain handset models. 

PCQ Labs