Many users on T-Mobile’s GSM wireless phone network have phones with the open to add a personal identification number (PIN) to their device in order to keep it secure. This code generally consists of four to eight digits. When PIN locked, the phone retains it’s emergency calling capabilities, but little else. However, when the wrong pin is entered three or more times, the phone, the SIM card inside, or both become locked. When this happens, the user may receive the message “SIM card is PUK locked” or “PUK required to unlock.”
