Smartphones are our gateway to communicating with others and consuming information. To access these features, you need a SIM card from a carrier. This SIM card assigns your phone a phone number and gives your phone an identity on the carrier’s network. If your high-end Android phone is stolen, you can get your SIM card locked by calling your carrier.

However, a thief could remove your SIM card from your phone and put it into another phone to use it for nefarious purposes. To prevent this, Android phones have a feature called SIM card lock that adds an extra layer of security to protect your SIM card. This guide discusses what a SIM lock is and how to activate it on your Android phone.

What is a SIM card lock?

A SIM card lock is a layer of security that prevents carrier services from being used unless the SIM is unlocked. This is different from a phone being carrier locked, which means that a phone can only use SIM cards from a certain carrier. The lock is in the form of a PIN, which must be entered each time the phone is turned on, even if the SIM is moved to a different phone. This prevents someone from using your SIM on your phone or another phone without knowing your SIM unlock PIN.

The reason for activating a SIM card lock is due to SIM phishing. Scammers use SIM phishing, also known as SIM swapping, to gain access to your SIM card to control your phone. For this, they collect as much of your personal information as possible from your social media and other accounts that use two-factor authentication or similar verification methods. Then they trick your carrier and its customer executive into believing you contacted them and asked them to transfer your number to a spare SIM card they (the scammer) own.

How to activate and modify a SIM card lock on an Android phone

Setting up a SIM card lock requires you to enter the default passcode set by your operator. The default SIM PIN is often on the packaging that comes with your phone, so make sure to save it when you get a new SIM. Make sure you know the default PIN before setting up the SIM card lock, as you will be locked out of your SIM after a few incorrect attempts.

1. Launch the Settings app.
2. Scroll down and select Security & Privacy.
3. Select More security settings near the bottom of the page.

4. Tap SIM card lock.
5. Flip on the Lock SIM card toggle. If you’re prompted to enter the default PIN, do so.

6. After it’s turned on, tap Change SIM PIN to change your PIN.

7. Enter your old PIN, then enter your new PIN, and tap OK. Be careful while entering your old PIN. Entering the wrong PIN three times blocks your SIM and requires you to get a new SIM.

You can test that this feature is working by restarting your phone. When the SIM is transferred to a different phone, whether an iPhone or Android, you can’t use it until it’s unlocked. Here’s what you see when you insert your locked SIM into another iPhone or Android device.

How to activate and modify a SIM card lock on a Samsung phone

Samsung phones have the One UI Android skin, which looks and functions slightly different from stock Android. Follow the steps below to set up a SIM card lock on your Samsung Galaxy phone.

1. Open the Settings app on your Samsung phone.
2. Scroll down and tap Security and privacy.
3. Select Other security settings.

4. Tap Set up SIM card lock.
5. Turn on the Lock SIM card toggle.

6. Enter your current SIM card PIN and tap OK.
7. Select Change SIM card PIN and enter a new passcode to protect your SIM.

What happens if I am locked out of my SIM?

If you accidentally locked your SIM card due to three failed attempts, your phone prompts you to enter a Personal Unlock Key (PUK), an eight-digit number. This number is located on the packaging your SIM card came in. If you don’t have the box, contact your carrier and verify yourself to get the PUK from them. We recommend storing your new SIM PIN in one of the top password managers on Android so you never lose it.

What if you have an eSIM?

You can still activate a SIM card lock if you have an eSIM. Even if you have a SIM card lock on a physical SIM, anyone can remove it and work on unlocking the SIM on another device. An eSIM is more secure because it can’t be removed from your phone, so it’s harder to unlock it without the SIM PIN. Follow the steps listed above to activate a SIM lock on an eSIM.

Prevent unauthorized access to your data

Adding a SIM lock to your phone is a great way to protect against SIM phishing and keep your accounts safe. You can take other steps to protect yourself and your device, such as good password hygiene. If you get too many spam calls and texts, you can block the spam callers or block the spam messengers. If you’re browsing your email inbox, there are easy ways to spot and report phishing emails to keep yourself and your community safe. If you click a phishing link, there are steps you can take to minimize data loss from phishing.