How to Turn On a SIM PIN on iPhone (2 Minutes)

A SIM PIN is a 4 to 8 digit code that locks your SIM card or eSIM, so it asks for the code every time the phone restarts or the SIM is moved to another phone. Turning it on takes about 2 minutes in your iPhone's Settings, and it stops a thief from using your number to receive your texts and sign-in codes.

Checked on 2 November 2026.

Why does a SIM PIN matter if your iPhone already has a passcode?

Your iPhone passcode locks the phone. It does not lock the SIM card inside it. A thief can take a physical SIM out of a stolen iPhone, put it in another phone, and receive your calls and text messages. Many banks and apps still send one-time sign-in codes by text message, so your phone number is a key to your accounts. A SIM PIN closes that gap: without the code, the SIM does not connect to the mobile network in any phone.

What do you need before you start?

You need your SIM's current PIN. Most carriers set a default PIN, often 1111, 1234 or 0000. Look it up on your carrier's website or on the card the SIM came on before you try it. Do not guess. After 3 wrong tries the SIM locks and asks for a PUK code, which only your carrier can give you. With the wrong PUK too many times, the SIM stops working for good and you need a new one.

How do you turn on a SIM PIN on iPhone?

Open Settings and tap Cellular (or Mobile Data, depending on your region).

If you have more than one line, tap the line you want to protect.

Tap SIM PIN and switch it on.

Enter your carrier's current PIN and tap Done.

Tap Change PIN, enter the current PIN, then type a new 4 to 8 digit PIN that is not your iPhone passcode and not your birthday.

Write the new PIN somewhere safe, such as your password manager.

Restart your iPhone once to check it: it should ask for the SIM PIN before the phone connects to the network.

Does a SIM PIN stop a SIM swap scam?

Only partly. A SIM PIN protects the SIM you hold. In a SIM swap scam, a criminal asks your carrier to move your number to a new SIM, and your SIM PIN does not stop that. To block it, ask your carrier for an account PIN or a number transfer lock, and use an authenticator app or passkeys instead of text-message codes where you can. Our guide shows the order for the accounts that matter most: Turn on two-factor authentication.

Does a VPN protect your phone number?

No. A VPN encrypts the internet connection between your iPhone and the VPN server, so people on the same Wi-Fi cannot see which sites and apps you use. Calls and text messages do not go through the VPN, and a VPN cannot lock your SIM. The SIM PIN and a carrier account PIN are what protect your number. More on the limits: What a VPN cannot protect you from.

Frequently asked questions

Does a SIM PIN work with an eSIM?

Yes. iPhone shows the same SIM PIN switch for an eSIM line, under Settings, Cellular, then the line.

Will I have to type the SIM PIN every day?

No. iPhone asks for it after a restart or when the SIM is moved to another phone. Face ID unlocks the phone as usual the rest of the time.

What if I forget my SIM PIN?

Stop after 2 wrong tries. Contact your carrier for the PUK code, enter it, and then set a new SIM PIN.

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