Your phone’s SIM card allows the device to make calls, send texts, and connect to the internet.
The SIM card provides a phone number that identifies your device on the carrier’s network, whether it’s T-Mobile, Verizon, or AT&T. It also ensures that you receive texts containing important information, such as banking alerts, verification codes, and personal messages.
So, knowing how to lock your SIM card to protect your data is essential.
Whether you have the latest 5G phone or a budget Android device, activating SIM lock is a straightforward process. This guide walks you through the steps.
What is a SIM card lock?
A SIM card lock is a layer of security, in addition to the screen lock, that prevents carrier services from being used unless the SIM is unlocked.
This is different from a cellphone being carrier-locked, which means a phone can only use SIM cards from a certain carrier.
The lock is a PIN, which must be entered each time the phone is turned on, even if the SIM is moved to a different phone. This extra layer of security prevents someone from using your SIM on any phone without knowing your SIM unlock PIN.
The SIM PIN is also different from your device’s lock screen PIN.
The SIM PIN is an extra layer of protection designed to prevent unauthorized access to your SIM card. The carrier service typically provides the PIN or can be changed in your phone’s settings.
Your device’s lock screen PIN protects unauthorized users from accessing your device’s apps and settings, using a PIN you’ve chosen.
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 and control your mobile device.
For this, they collect as much personal information as possible from your social media and other accounts.
Then, they trick your carrier and its customer service executive into believing you contacted them and asked them to transfer your number to a spare SIM card they (the scammer) own.
A SIM card lock, however, prevents the scammer from gaining access to the SIM and the carrier’s network through it.
When setting up a SIM card lock, ensure you change your default PIN! Your carrier’s default SIM PIN (for example, 0000 or 1234) is easily guessable. For maximum security, immediately change it to a unique PIN that only you know after activating the SIM lock.
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.
Some carriers might have specific apps or websites where users can manage SIM PINs or find PUK (PIN Unlock Key) codes.
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.
If you enter your SIM PIN incorrectly three times, your SIM card will be locked, and you’ll need a PUK code from your mobile carrier to unlock it.
Entering the PUK incorrectly too many times (usually 10 times) will permanently disable your SIM card, requiring you to get a new one from your carrier.
Use your PUK code only when absolutely necessary.
- Launch the Settings app.
- Scroll down and select Security & Privacy.
- Select More security settings near the bottom of the page.
- Tap SIM card lock.
- Turn on the Lock SIM card toggle.
- You may be prompted to enter the default PIN.
- After it’s turned on, tap Change SIM PIN to change your PIN.
- 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 if this worked by moving your SIM to a different mobile 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:
Turning on the SIM lock may differ from one phone to another. Use the search box in your phone’s Settings app to search for SIM lock and activate it.
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.
- Open the Settings app on your Samsung phone.
- Scroll down and tap Security and privacy.
- Select More security settings.
- Tap SIM card security.
- Turn on the Lock SIM card toggle.
- Enter your current SIM card PIN and tap OK.
- 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 get locked out due to entering an incorrect PIN three times, 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.
Store your new SIM PIN in one of the top password managers on Android so that you never lose it.
What if you have an eSIM instead of a physical SIM card?
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 protects against SIM phishing and keeps your accounts safe. You can take other steps to protect yourself, such as good password hygiene.
If you get too many spam calls and texts, block the spam callers or block the spam messengers. There are also ways to spot and report phishing emails to keep yourself and your community safe.
