What is a PUK code? How to Find Yours

Key takeaways

• A PUK code (Personal Unblocking Key) is an eight-digit code used to unblock a SIM card after you enter the wrong SIM PIN three times in a row.
• A PUK code is printed on the plastic card that the SIM came in, and you can also ask your network for it. SMARTY customers can do this through webchat.
• A SMARTY SIM allows 10 attempts to enter a PUK code. After 10 failed attempts, the SIM is permanently blocked and must be replaced.

 

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Your phone restarts after an update. Instead of the usual lock screen, it tells you your SIM is blocked and asks for a PUK code. You didn't set one, you've never heard of one, and you'd quite like to make a phone call.

Take a breath. This is a very common problem, and it's usually sorted in a few minutes. Here's what a PUK code is, where to find yours, and how to use it without making things worse.

What is a PUK code?

A PUK code is an eight-digit code that unblocks a SIM card after you enter the wrong PIN three times. The network gives each SIM its own PUK when it’s issued, so you can’t choose or change it. Think of it as the spare key for your SIM's PIN.

Why is my phone asking for a PUK code?

A SIM PIN is a short code that prevents anyone from popping your SIM into another phone and using your number. If you enter the wrong PIN three times in a row, the SIM locks itself and asks for the PUK instead.

It usually happens when:

• A phone restarts and the SIM PIN is mistyped.
• A SIM is moved to a new phone and the PIN has been forgotten.
• Someone else, such as a curious child, taps away at the keypad.

Two bits of reassurance. A blocked SIM doesn't delete your photos, contacts or apps. It just stops the SIM from working. And your phone should still let you make emergency calls to 999 or 112.

Where is the PUK code on a SIM card?

Not on the SIM itself, which is far too small for anything but a serial number. The PUK code is printed on the credit-card-sized plastic card that came with the SIM, usually on the back. If that card is still in a drawer somewhere, you're done.

If you use an eSIM, there's no card to check, so you'll need to ask your provider for the PUK instead.

How to get a PUK code if you've lost the packaging

Lost the card? That's the most common situation, and it's fine. The network that issued the SIM keeps a record of the PUK code and can give it to you.

1. Connect the phone to Wi-Fi, or use another internet-connected device. A blocked SIM can't give you mobile data, calls or texts, but Wi-Fi on the phone should still work
2. Check your network's app or online account. Many networks show the PUK code there.
3. If it isn't there, contact your network by webchat or phone. They'll want to check it's really you before sharing it, which is exactly what you'd want a network to do.

Can you get a PUK code by text?

Usually not. Most networks don't send PUK codes by text, and a blocked SIM can't receive texts anyway. If a message arrives claiming to be your PUK or offering to sort out your SIM, treat it with suspicion.

Beware of PUK code generators

Searching for PUK help may lead you to websites that claim to "generate" or "recover" your PUK code, sometimes for a fee. Your network issues the PUK code, so these sites can't know it. And your network shouldn't charge you for it. Don't pay anything or share account details with a third-party site. Go straight to your network.

Is a PUK code the same as a network unlock code or a PAC code?

Mobile codes can sound similar. Here's a quick guide:

Code	What it does
SIM PIN	A SIM PIN is a short code you enter to use your SIM. It protects your number if the SIM ends up in another phone.
PUK code	A PUK code is an eight-digit code that unblocks a SIM card after the wrong SIM PIN has been entered three times.
Network unlock code	A network unlock code removes the lock that ties a phone to one network, so you can use a SIM from a different network.
PAC code	A PAC (Porting Authorisation Code) lets a mobile number move from one network to another.

If you're moving your number, our guide to PAC and STAC codes explains how to get one.

FAQs

1. How many attempts do you get to enter a PUK code?

Most UK networks, including SMARTY, allow 10 attempts to enter a PUK code. After 10 failed attempts, the SIM card is permanently blocked and must be replaced.

2. Can you unlock a SIM card without a PUK code?

No. A blocked SIM card can only be unblocked using its PUK code, which the network that issued the SIM keeps on record. The alternative is a replacement SIM card from the provider.

3. What is the difference between a PUK code and a PAC code?

A PUK code unblocks a SIM card after three incorrect PIN entries. You need a PAC code to transfer a mobile number from one network to another.