Xiaomi’s modern smartphones store vast amounts of sensitive information, access to which is often tied to a mobile phone number. SIM-The first and most important step in protecting against unauthorized access in the event of loss or theft of a device, which many users neglect to rely solely on a pattern lock or fingerprint, but this is a flawed security strategy.
MIUI and HyperOS have a robust security mechanism that requires you to enter a special code every time you turn on your phone or retrieve your card, preventing attackers from using your number to access banking applications or social media accounts, which takes only a few minutes to enable, but provides a critical level of privacy protection.
Before you start setting up, you need to make sure you know the standard PIN-It's a code provided by your carrier, usually on a plastic card that came with a SIM card or is included in a contract. If the code was lost, it can be restored through the operator’s personal account or by contacting the communication salon, but until that point it is better not to activate the password request, so as not to block the card.
Preparation for activation of protection SIM-map
The first step before locking is to find the standard security codes, and the carriers assign each chip a unique security code. PIN-code (usually 0000 or 1234 for new cards, but better to check) If you enter the wrong code three times in a row, the SIM card will be temporarily blocked and you will need to enter a more complex one. PUK-code.
It is recommended to preserve in advance PUK-code in a secure location, such as a cloud storage or a notebook, which is 8 digits long and is required to unlock the card after repeatedly entering the wrong card. PIN. No PUK-It is impossible to restore access to the SIM card, and you will have to reissue it from the operator.
⚠️ Warning: Never keep it. PUK-If the device is stolen, an attacker can easily find the SIM card unlock code along with the phone itself.
It’s also worth checking if you have operator-sided SIM protection activated. Some providers offer additional layers of security that work regardless of the settings of the Xiaomi or Redmi smartphone itself.
Step-by-step instructions for enabling lock in MIUI and HyperOS
The process of activating protection in Xiaomi shells is quite standardized, but the names of items may vary slightly depending on the Android version and regional firmware. To begin, open the main menu and find the Settings app. Privacy Protection (or Passwords and Security) → Confidentiality SIM-maps (or lockdowns) SIM-map).
In the menu that opens, you will see a switch opposite your SIM card (if there are two, the settings will be for each separately). Activate the slider. The system will immediately request the input of the current one. PIN-Enter the code you found on the plastic card or installed earlier, and once you've entered it, the security will be activated.
☑️ Pre-insertion check
Now, every time you turn on the smartphone or after removing the SIM card and re-installing it, the phone will request input. PIN-Without it, make calls, send them. SMS It is impossible to use the mobile Internet even if you move the card to another phone.
Setting up for two SIM-map
Most Xiaomi and Redmi models support two SIM cards at the same time, and it is important to understand that lock settings apply individually to each slot, you can only turn on protection for the main card used for banking applications, and leave the second one free if it does not have important information.
In the control menu SIM-The maps display two separate switches, so you can flexibly adjust the security level. For example, if the second card is used only for the Internet or courier calls, its blocking may be unnecessary, while the main card with associated accounts must be protected.
| Parameter | SIM 1 (Main) | SIM 2 (Additional) |
|---|---|---|
| Blocking status | Included. | Off. |
| PIN request upon activation | Yes. | No. |
| Access to contacts | Only after you enter the code. | Always open. |
| Risk of data loss | Minimum | Medium. |
When changing SIM card slots (for example, when repairing a phone), security settings are saved behind the slot or reset depending on the version of the software, so after such manipulations it is better to recheck the lock status in the settings menu.
What to do when blocking and entering PUK-code
If you have entered three times incorrectly PIN-code, the SIM card is blocked, and the phone will request PUK-Personal Unblocking Key is a security mechanism that prevents password selection by brute-force. PUK You have to be careful, you only have 10 attempts.
For input PUK-The lock screen usually has a special button or field that appears after the attempts to enter are exhausted. PIN. Enter the 8-digit code you received from the operator, and then the system will suggest you to come up with a new one. PIN-code (from 4 to 8 digits) and confirm it by re-entering.
Where to find out. PUK-code if card is lost?
⚠️ Note: After 10 failed attempts to enter PUK-The SIM card is permanently blocked, and it cannot be restored, and you will need to purchase a new SIM card with a number saved through the operator's office.
Shift. PIN-code-in-house
Standard codes like "0000" or "1234" are too easy to guess, and once you've locked, it's highly recommended that you change the PIN to a unique one that only you know, and you can do this from the same menu where the lock was enabled.
Select the option Change. PIN-The system will first ask you to enter the current (standard) code, and then ask you to enter a new code twice for confirmation. Come up with a combination that is difficult to guess, but easy to remember. Avoid birth dates or repeating digits.
- 🔒 Use combinations of 6-8 numerals.
- 🧠 Write the new code to a safe place immediately after the change.
- 🔄 Change. PIN-code periodically, for example, once every six months.
If you forget your own PIN-code, the recovery procedure is the same as when using the standard - through input PUK-So the code is there. PUK-Code is a critical condition for using the lock function.
Remote blocking via Google and Xiaomi Cloud
It is important to distinguish between locks SIM-map (PIN-code) and lock the device itself if the phone is lost, PIN-The SIM card code will protect the number from being used on another device, but will not protect the data inside the phone if an attacker can turn it on (for example, through Safe Mode, although modern versions of Android limit this to the number of users).
For full protection, use Google Find Device and Xiaomi Cloud, which allow you to remotely lock the screen, display a message on the screen or completely erase data, but these features only work if the phone is on and has Internet access.
💡
Turn on Find Device in your Google account settings in advance, allowing you to remotely lock your phone without even having to lock it. SIM-cards if the device connects to Wi-Fi.
Lockdown SIM-Cards and locking your device through cloud services are complementary measures, the first protecting your number and access to your device. SMS-code, the second protects files and access to the smartphone system.
Frequent problems and their solution
Users may experience a situation where the phone stops accepting input. PIN-or constantly writing "incorrect" PIN", It's often due to software failure or damage to the SIM card contacts.
Try removing the SIM card, wipe the contacts with soft dry cloth and paste back in. Make sure the card is set correctly according to the shape of the tray. If the problem persists, check the card on another phone. If there is an error there, it may be that the chip is physically damaged.
- 📱 Reboot your smartphone before you try again.
- 💿 Check the SIM card in another device to prevent a phone breakdown.
- 🛠 Update the firmware MIUI/HyperOS last-minute.
💡
If the phone is not receiving the correct PIN-code after rebooting and cleaning contacts, contact the operator to replace the SIM card - it may have failed.