A personal unblocking code (PUC), also known as a Personal Unlocking Key (PUK), is used in 3GPP mobile phones to reset a personal identification number (PIN) that has been lost or forgotten.
Most mobile telephones offer the feature of PIN protection. After switching on the phone, if the PINi security function is active, the user is requested to enter a 4-8 digit PIN enabling the phone's non-emergency calling functions. If the wrong PIN is typed in more than three times, either the SIM card, the device, or both become locked. They can be returned to their original unlocked state by entering a PUC...