PIN (Personal Identity Number) is a 4-8 digit access code which can be used to secure your telephone from use.

PIN2 (Personal Identity Number 2) is a 4-8 digit access code which can be used to access the priority number memory and cost of calls.

The PUK (Personal Unblocking Key) and PUK2 are used to unlock the PIN and PIN 2 codes respectively if your SIM card is blocked.