What Does "SIM Card Is PUK Locked" Mean on My T-Mobile Phone?

By Shea Laverty

When your SIM card is security locked, the PUK is the only way to unlock it.
i George Doyle & Ciaran Griffin/Stockbyte/Getty Images

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."

Personal Unblock Key

A Personal Unblock Key, or PUK, is a code associated with SIM cards in mobile phones. This code is designed to unlock a SIM card that has been locked due to incorrect PIN entry. Without the proper code, there is no way to unlock the card and enable your phone's functions.

How PUKs are Activated

When you incorrectly input your PIN three or more times on your phone, the SIM card will automatically lock and assign a PUK. This also occurs when your phone or SIM card is reported lost or stolen, and a network operator decides to lock the SIM card for security reasons.

How to Unlock the SIM Card

When your SIM card is locked and requires a PUK, there is only one option: Call T-Mobile Customer Care. Only they can legally provide you with the PUK code to unlock your phone, and they will be the most effective at ensuring your device returns to working order. Once you have contacted them, you will provided the PUK code and instructions on how to enter it on your phone to unlock the SIM card.

SIM Card Invalidation

It's very important that you not try and unlock your SIM card yourself. The PUK is a security system in place to protect your SIM card's security, and it will do so at any cost. If you incorrectly enter the PUK ten times, the SIM card will be invalidated. There is no code, procedure, or tool to re-validate your SIM card. Once it has been invalidated, it is permanently locked and the card must be replaced, at the consumer's expense.