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How to protect your phone with a SIM lock



Mobile device showing a PIN entry screen

Most people know to protect their phone with a PIN code. But you can also protect your phone’s SIM card. A SIM card is what enables you to make calls and send messages. It’s the little chip given to you by your service provider (for example EE, O2, Vodafone) that you put into your phone.

When locking your SIM card, you need to be very careful - entering your SIM code incorrectly three times will cause it to stop working and will mean that you’ll need to call your provider for help to access it again.

If your phone is stolen and the thief finds that they can’t get into your phone to access your text messages or receive calls, they might try to put your SIM card into another phone. This could enable them to gain access to security messages sent via SMS (text). For example, text messages that approve an online payment with a code sent from a bank, or a message to provide a security code when adding your card to a new mobile wallet.

A SIM lock is an extra layer of protection that can be put in place on your phone. When it’s in place, it means you will need to provide a numeric PIN to unlock your SIM, before it can be used.

SIM lock is not available on all phones and may require your service provider’s default code, which you can find out by contacting your service provider, for example EE, O2 or Vodafone.


To set up a SIM lock you usually need to go to the security section within your phone settings. For phones that don’t have security sections, try using the search bar to find ‘SIM lock’. If nothing comes up, this usually means your phone does not support SIM lock.

If you can find the SIM lock menu, you should then have two options: turn on SIM lock or change the PIN.

First, you need to turn on the SIM lock. But to turn on the SIM lock, you will need to know the SIM lock PIN code. If you don’t know the code, then contact your service provider for further advice. Once you have access, you can change the PIN to one of your own choice.

You can learn more about the SIM lock for Android at How-to Geek.


For iPhones, go to Settings > Phone > SIM PIN. From there, you can turn it on and change the SIM PIN. Again, you will first need to know the SIM PIN to turn on the lock, so if you don’t know what it is, contact your service provider for further advice

What happens if I enter the wrong code for my SIM lock?

Entering the wrong PIN for your SIM three times will block your SIM. The process to unblock your SIM could take time and you’ll need to contact your service provider for help.

You’ll need to use a different phone, as you won’t be able to use your phone for calls or messages while the SIM is blocked. That’s why it’s best to contact your service provider to find out what your PIN is when you first try to lock it, provided your phone has one set up already.

Change the SIM PIN

After you’ve turned on the SIM lock, it’s a good idea to change the PIN for the SIM. Always use a unique PIN for every app, device or card. Explore our article on PINs and passwords for more advice on staying safe.

Remember that to move your locked SIM to another phone you’ll need to disable the SIM lock feature first, so make your PIN a memorable one.