PIN code and PUK code: what they are and how to use them

November 6, 2025

Your SIM card PIN and PUK codes are essential for keeping your mobile phone secure. But what if you forget your SIM card PIN, or if you want to change it? In this blog, we’ll explain what the PIN and PUK codes are, what you use them for, and what to do if you run into problems.

What does a SIM card do?

You need a SIM card to connect your phone to your provider’s mobile network. This SIM card is protected with a PIN code. Only after you enter the correct PIN does your SIM card connect to the network, and you can then use your Prepaid credit or Sim Only bundles. But what can you do if you forget your SIM PIN? Don’t worry: there are solutions, so you can get access again.

What’s the difference between a PIN and a PUK code?

Any SIM card has both a PIN and a PUK code. You’ll use the SIM PIN more often than the PUK code, as you need it to unlock the SIM card. The PUK code only becomes important if you enter the wrong PIN three times and the SIM card gets locked.

Your SIM's PIN code: key to unlocking your SIM card

The "PIN" in PIN code stands for Personal Identification Number, a four-digit code. You enter this code when you start your phone or insert the SIM card. This protects your SIM card, so no one else can make calls, send texts, or use data without the code. Only an unlocked SIM card can connect to the mobile network.

It's important to note that your SIM card's PIN code is not the same as your phone’s lock code. It can be confusing, since that code is often also four digits (or six on an iPhone). On Android, the exact length varies by manufacturer. That unlock code is one you chose when you first set up your phone. So make sure not to mix the two up when unlocking your SIM card.

How do I know my PIN code?

At Simyo, we always send the PIN and PUK codes by post. After activating your SIM card, you’ll also receive them by email. Are you not a Simyo customer (yet)? Check the documentation you got from your provider when you purchased your SIM card. The PIN is often printed on the SIM holder or in a letter. If you’ve lost it, you can ask your provider for the default PIN or log in to your online account.

At Simyo, you can also find your SIM's original PIN in Mijn Simyo or the Mijn Simyo app. You will only see the original PIN code here. Have you changed the PIN code for your SIM card? If so, you will not be able to find it in Mijn Simyo, but you can change the PIN code by entering the PUK code.

To find your SIM card's original PIN code:

Go to Mijn Simyo on your computer or open the app on your phone.
Log in with your phone number and password.
Tap on ‘Instellingen' (Settings).
Tap the ‘Simkaart' (SIM card) tab.
Next to ‘Pincode' (PIN code), click on 'Tonen' (Show) (or the eye icon in the app).
You’ll now see your original PIN code.

How to change the PIN code of your SIM card

Simyo SIM cards come with an automatically generated PIN. Some other providers use simple default PINs like 0000. For security, it’s a good idea to change your SIM PIN, which you can do yourself in just a few steps!

On iPhone

Open the Settings app.
Tap 'Mobile Data'.
Tap 'SIM PIN'.
Tap 'Change PIN.”
Enter your current SIM PIN.
Enter and confirm your new PIN.

On Android

These steps can vary per Android phone:

Open the Settings menu.
Tap 'Security & Location'.
Tap 'Advanced'.
Tap 'SIM card lock'.
Tap 'Change SIM PIN'.
Enter your current PIN, then set a new one.

Did you forget your SIM PIN?

You have three tries to enter the right SIM PIN. If you enter it wrong three times, the SIM card will be blocked. You won’t be able to call, text, or use data. There is a solution to fix this: your PUK code.

What is a PUK code?

PUK stands for Personal Unlock Key. It’s an eight-digit code that unlocks a blocked SIM card. Unlike a PIN, the PUK cannot be changed.

If your SIM card is blocked because you entered the SIM PIN wrong three times, enter the PUK code to set a new PIN without needing the old one. After that, you’ll be reachable again. If your phone doesn’t accept the PUK code, try it with another phone.

Where can I find my PUK code?

At Simyo, you’ll receive your PUK code by email after activating your SIM. With other providers, it’s often printed on the SIM holder or available via customer service. Many providers also offer online tools to retrieve it.

At Simyo, you can also find it in Mijn Simyo or the Mijn Simyo app:

Go to Mijn Simyo or open the Mijn Simyo app.
Tap on ‘Instellingen' (Settings).
Tap the 'Simkaart' (SIM card) tab.
Next to ‘Pukcode' (PUK code), click on 'Tonen' (Show) (or the eye icon in the app).
You’ll now see your PUK code.

What if I enter the wrong PUK code?

You have ten tries to enter the correct PUK. If you fail all ten times, the SIM will be permanently blocked and unusable. In that case, you’ll need to request a replacement SIM card through Mijn Simyo or the app. You’ll then receive a new SIM with a new PIN and PUK.

So don’t worry if you make a typo once, it happens! But never try to guess your PUK if you don’t know it. Log in to Mijn Simyo to find the right one. Once you’ve found it, you can reset your SIM PIN if needed.

Keep your codes safe

Your SIM PIN and PUK codes are essential for the security of your SIM and to make sure you stay reachable. Whether you’re with Simyo or another provider, keep these codes somewhere safe and know how to recover or change them if needed. That way, you’ll always stay connected.