How to Enable SIM Card PIN Lock on Xiaomi Phone to Prevent Unauthorised Use

Most people lock their phone screen, but far fewer lock their SIM card. If your Xiaomi phone is stolen, the thief can simply remove your SIM and insert it into another phone to receive your calls, 2FA SMS codes, and bank OTPs. A SIM PIN blocks this instantly.

What Is a SIM PIN?

A SIM PIN is a 4–8 digit code tied to your physical SIM card (not your phone). Every time the SIM is inserted into any phone and the device powers on, the PIN must be entered before the SIM can make calls or access mobile data.

It is separate from your phone screen lock.

How to Enable SIM PIN on Xiaomi HyperOS

1. Go to Settings → Passwords & security → Privacy.
2. Scroll down and tap SIM card lock (or Set up SIM card lock).
3. If you have two SIMs, select SIM 1 or SIM 2.
4. Toggle Lock SIM card to ON.
5. Enter your current SIM PIN when prompted.

Default SIM PIN: If you have never set one, your carrier's default is usually 0000 or 1234. Check your SIM packaging or call your carrier to confirm.

How to Change the SIM PIN

1. Settings → Passwords & security → Privacy → SIM card lock.
2. Select the SIM.
3. Tap Change SIM PIN.
4. Enter the old PIN, then your new PIN twice.
5. Confirm.

⚠️ Critical Warning: PUK Code

If you enter the wrong SIM PIN 3 times, your SIM is blocked. To unblock it, you need a PUK (Personal Unblocking Key) from your carrier. Entering the wrong PUK 10 times permanently destroys the SIM — you will need a replacement.

Before enabling SIM PIN:
- Note your default PIN from carrier documentation.
- Call your carrier and ask for your PUK code — store it somewhere safe (not on the phone).

SIM PIN vs Phone Screen Lock — Key Differences

Feature	Screen Lock	SIM PIN
Protects phone access	✅ Yes	❌ No
Protects SIM in other devices	❌ No	✅ Yes
Stops SMS 2FA theft	❌ No	✅ Yes
Required on every reboot	❌ No	✅ Yes

Recommended Security Combo

For the strongest protection, use both:
1. Screen lock (fingerprint + PIN) to protect phone access.
2. SIM PIN to protect the SIM from being used elsewhere.
3. Mi Account Find My Device to remotely lock/erase if the phone is lost.

Pro Tip

After enabling SIM PIN, you will need to enter it every time you restart your phone. Choose a PIN you can remember easily but is not an obvious sequence like 1234. Never use your birth year — it is the first thing a thief tries.