SIM and phone PIN codes: why you need them and how not to lock your SIM

A PIN is a short numeric password. A SIM PIN (4-8 digits) stops your SIM being used in someone else's phone. A screen unlock PIN protects the phone itself. A bank card PIN is a separate story.

A SIM PIN is a lock on your letterbox

In plain words

A SIM PIN is like a lock on your letterbox: even if someone pulls out the box (the SIM card) and takes it home, they cannot read your post without the code. A screen PIN is like the lock on your front door: it protects everything inside the phone.

How it works

The SIM PIN is requested when you turn on the phone or put the SIM into another device.
After three wrong attempts, the SIM locks.
Only a PUK code can unlock the SIM.
The screen PIN is checked by the phone, not the operator.
Biometrics (fingerprint, face) work alongside the PIN, not instead of it.

PIN and biometrics working together

Where you'll see it

The SIM PIN is on the plastic card the SIM came in or in your contract. You can turn it on or change it in your phone's security settings ("SIM card lock"). The screen code is set under "Security" or "Lock screen".

Does it matter when buying

I recommend turning on the SIM PIN: if your phone is stolen, the thief cannot put your SIM into another device and receive your bank's text codes. And use a strong screen code - not 1111 and not your date of birth.

Myths

Myth: The SIM PIN and screen code are the same thing. Reality: They are different codes: one for the SIM, the other for the phone.
Myth: A fingerprint completely replaces the PIN. Reality: After a restart, the phone will still ask for the PIN.

FAQ

What if I enter the wrong SIM PIN three times?

Enter the PUK code or contact your operator.

Where do I find my SIM PIN?

On the plastic card the SIM came in, or from your operator.

Which screen PIN is safer?

Six digits or more with no obvious patterns, or a password.