SIM card locked? How to enter the PUK code and get your phone working again

A phone that suddenly says SIM Locked, Enter PUK or SIM PIN is not broken. It is doing what it was set up to do. The SIM has a security PIN, three wrong entries blocked it and now it needs a longer unlock code from your carrier. The fix is simple, but one mistake can ruin the SIM, so go carefully. Below are the steps for iPhone and Android, how to find the PUK and what to do if the SIM is blocked.

PIN, PUK and phone passcode: what is the difference?

• SIM PIN: a four to eight digit code that locks the SIM card itself. The phone asks for it when it restarts or when you put the SIM in another phone.
• PUK: the PIN Unlock Key, usually eight digits. It resets the SIM PIN after too many wrong attempts.
• Phone passcode: the code that unlocks your screen. It is unrelated to the SIM.
• Account PIN: the carrier's code for customer service. It is not the SIM PIN either.

Step 1: make sure you really need the PUK

If the phone asks for a SIM PIN and you still have attempts left, try the PIN once more. If you never set a PIN, the carrier may have used a default. Carriers often use a default code, such as 1111, 0000 or 1234, but it differs, so check your carrier's help page before you guess. Be careful, since each wrong try counts. After three wrong attempts, the SIM is locked and asks for the PUK. Stop guessing at that point.

Step 2: get your PUK code

Step 3: enter the PUK on your phone

How to turn the SIM lock off (or on)

The SIM lock is a security feature. It stops a thief from putting your SIM in another phone and using your number. If you do not want it, you can turn it off, but you need the current PIN to do it. If you want the extra protection, leave it on and choose a PIN you will remember.

• iPhone: go to Settings › Cellular › SIM PIN, and turn SIM PIN off or on. Enter the PIN to confirm. On a dual SIM iPhone, choose the line first. If you do not see this setting, your carrier may not support it.
• Samsung: go to Settings › Security and privacy › More security settings › Set up SIM card lock, then toggle Lock SIM card. Menu names vary by version.
• Pixel and other Android: go to Settings › Security & privacy › More security & privacy › Encryption & credentials or SIM lock, depending on your version, and toggle Lock SIM.

Why is my SIM asking for a PIN?

• You, or someone else, turned on SIM PIN in settings.
• You put the SIM in a new phone, which asks for the PIN to confirm.
• The carrier shipped the SIM with a PIN lock turned on.
• The phone restarted after an update or a crash, and SIM PIN asks after every restart.
• Someone tried to use your SIM in another device, and it locked.

If you did not set it and you are not sure how it got locked, think about whether someone had access to your phone. Check your account for changes, and consider adding a carrier PIN. See how SIM swap scams work.

If the SIM is permanently blocked

Still no service after unlocking?

If the SIM is unlocked but the phone still has no signal, the cause is likely something else. Restart the phone, toggle Airplane Mode and check the carrier for outages and account status. See what to do when an iPhone has no service or what to do when a Samsung says not registered on the network.

Getting the PUK from US carriers

• Verizon: sign in to My Verizon, open the device, and look for the SIM PIN and PUK option, or call 611 from another phone (1-800-922-0204).
• AT&T: the PUK is shown in the myAT&T app or website under your device settings, or call AT&T support.
• T-Mobile: sign in to T-Life or T-Mobile.com and look under your line's device settings, or call 611 from another T-Mobile phone.

Menu names change, so if you cannot find it, search the carrier's site for PUK. Support will verify your identity before giving the code, so have your account PIN ready.

Does an eSIM have a PIN?

Yes. An eSIM can have a SIM PIN just like a physical card, and the same PUK rules apply. If an eSIM gets locked and the PUK fails, the carrier can send a new eSIM to the phone without you visiting a store.

Is a SIM PIN worth keeping on?

A SIM PIN stops someone from taking your SIM card and putting it in another phone to receive your texts and verification codes. That makes it a useful layer against account takeovers if your phone is stolen. The downside is entering it after every restart. If you keep it on, change the default PIN to your own and store it in a password manager.

What not to do

• Do not keep guessing the PIN. Three wrong tries lock it.
• Do not guess the PUK. Ten wrong tries usually block the SIM for good.
• Do not trust websites or apps that offer to generate a PUK. Only your carrier has it.

Change the default SIM PIN

If you keep the SIM PIN on, replace the default code with your own. On iPhone, go to Settings › Cellular › SIM PIN › Change PIN. On Samsung, look in Settings › Security and privacy › Other security settings › Set up SIM card lock.