Owners of smartphones Xiaomi, Redmi and POCO They often think about the security of their data, forgetting about the very first line of defense, the SIM card. PIN-SIM code is a critical step that turns your SIM card into a useless piece of plastic for anyone who steals a phone or simply removes a chip from the device. Even if an attacker tries to insert your SIM into another device, without the code, he will not be able to make calls or use the mobile Internet.
Shell interface MIUI or HyperOS offers a lot of privacy settings, but the SIM lock feature sometimes hides in the back of the menu or works less clearly for beginners. In this article, we will detail how to activate the protection, what to do if you forget the code, and how to use it correctly. PUK-Unlock code so you don’t lose access to the number forever.
Many users ignore this setting, relying only on a pattern lock or fingerprint to unlock the screen. However, this is a misconception: while the phone is on, the SIM card is available for use, but once the device reboots or discharges, the lack of a password on the SIM opens the door to scammers who can intercept confirmation codes from SMS from banking applications.
Why do you need a lockdown? SIM-maps in Xiaomi smartphones
The main purpose of setting a password on a SIM card is to protect your phone number from unauthorized use in the event of theft or loss of a gadget. If a Xiaomi smartphone is stolen and turned off, a thief will not be able to turn it on without a screen password, but if he simply extracts the SIM and inserts it into his phone, he will have full access to your number, which threatens not only financial losses from calls, but also access to accounts that use two-factor authentication.
In addition, blocking the SIM card creates an additional level of complexity for the attacker, and even if he manages to bypass the lock screen (which happens in rare cases of vulnerabilities), the SIM card will remain a lock that he will not be able to open. PIN-The code is stored on the SIM card chip itself, not in the phone’s memory, so resetting your smartphone settings or flashing it will not remove this protection.
⚠️ Warning: Never install simple combinations like 0000, 1111 or 1234. Attackers often try these standard codes first, especially if the phone was picked up in an unlocked state.
It is important to understand the difference between codes. PIN-A code is your personal password that you invent or change. PUK-The code is a master code for unlocking, which is issued by the carrier. PIN, The SIM will be blocked and will be required. PUK. After ten false attempts to enter PUK SIM card is permanently blocked and will have to be replaced by the operator.
Preparation for the installation of protection: search for PUK-code
Before activating a password request when enabled, it is strongly recommended to find and write PUK-This is your lifeline when you forget your invented one. PIN-code or block the SIM with an erroneous input. PUK-The re-access to the SIM card is possible only through a visit to the operator’s office with a passport, which takes time.
Where do you look for this code? Most often it's on the plastic base card from which you squeezed your SIM card when you bought it, usually a field labeled PUK or PUK code, closed with a security layer, and if the plastic base is lost, the code can be found in the mobile operator's personal account on the website or in the official application.
The paths to receive the code may differ for subscribers from one operator to another, but the algorithm is the same: login to your personal account by phone number (via SMS or password) and the SIM card settings section, and you can also find the code by calling the operator's support if you can make a call from another number.
Where else to find. PUK-code if the card is lost?
Write it down. PUK-It doesn't make sense to keep it in the notes of the phone you're going to protect, because when you lock the SIM, it can be difficult to access those notes.
Step-by-step instructions: how to include a request PIN-code
The process of activating the password for the SIM card in Xiaomi smartphones with MIUI 12, 13, 14 shells and the new HyperOS is almost identical. The settings interface is standardized, so you can easily find the desired menu item. Before you start, make sure that the SIM card is installed in the phone and defined by the network.
First, go to the main settings menu, and then open the Settings app (the gear icon) on your desktop or in the notification curtain, and then look for the connection and networking section. Depending on the firmware version, it may be called "Passwords and Security" or be directly in the section "SIM-maps and mobile networks".
The most direct way in modern versions MIUI It looks like this: go to Settings → Passwords and security → Privacy. However, in most cases, the SIM control unit is separately installed. → SIM-Select a specific SIM card if you have two (SIM 1 SIM 2) because the settings for each may be different.
☑️ Algorithm for introducing protection
After selecting a SIM card, find the Settings item SIM-card or switch immediately request PIN-The system will ask you to enter the current code. PIN-If you've never changed your factory settings, try the standard combinations: 0000, 1111 or 1234. If none fit, don't try to guess any further - refer to the contract with the operator so that you don't block the card.
Once you have successfully entered the old code, the system will suggest you come up with a new one, enter the desired combination of numbers (usually 4 to 8 characters) and confirm it by re-entering, and from now on, every time you reboot your phone or retrieve your SIM card, a window will appear to ask you to enter a PIN.
Configure security and lock parameters
In the SIM card management menu in Xiaomi, you can not only turn on and off the password request, but also other important parameters. PIN-code if you think the current one is too simple, or if you used a standard factory code.
The code change function is useful for periodic updates of security measures. PIN-code every few months, especially if other people have used the phone or if there is a suspicion that the code may have been noticed. PIN-code SIM same-menu.
Also, this section often displays network status and network type (4G/5G). Make sure that once you set a password, the phone logs in correctly. Sometimes, with the protection on, the phone can search the network longer after you turn on, which is normal behavior, since the SIM card is authorized first.
| Parameter | Description | Recommended value |
|---|---|---|
| Request. PIN-code | Require password entry at start | Included. |
| Old PIN | Current access code (factory) | 0000 / 1234 |
| New PIN | Your personal code. | Unique combination |
| Limit of attempts | Number of errors before blocking | 3 attempts at |
Note that in some custom builds or older versions of MIUI, the path may be slightly different. If you don't find a paragraph in Passwords and Security, search by settings. Type the word "SIM" or "PIN" into the settings search bar and the system will suggest the desired section.
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Use a code that is easy to remember but hard to guess, such as using not a date of birth but a part of an old home phone number or a combination associated with your hobby.
What to do if the SIM card is blocked (PUK-code)
If you have entered three times incorrectly PIN-code, the SIM card will be blocked, and the phone will require input PUK-It's not a cause for panic if you follow the advice from the beginning of the article and save the code, and the screen will show a message saying "Sim card locked" or "Enter" PUK-code".
Enter the 8-digit PUK-The code you found on a plastic card or in your personal account, and when you enter it successfully, the system will immediately ask you to come up with a new one. PIN-Enter the new combination twice to confirm, and then the SIM card will be unlocked and ready to go.
⚠️ Note: You only have 10 attempts to enter PUK-Every error reduces the counter. If the counter reaches zero, the SIM card will be permanently damaged by software, and you can't restore it, you have to buy a new SIM with the number saved.
Enter. PUK-It's better to double-check the code in the operator's office than to take risks if you can't find it. PUK-code by any means, the only solution is to contact the communication salon of your operator with a passport for reissuing a SIM card.
Typical problems and their solution
Xiaomi users may encounter a number of specific problems when setting up protection. One common is that the phone doesn't accept the correct security. PIN-This can occur if the SIM card is physically damaged (scratches on the contacts) or if the failure occurred on the carrier side.
Another problem is that you can request code endlessly after you reboot, even if you have the code entered correctly, and then you can clean the cache of the Phone system application or "SIM-Manager. Go to Settings for that. → Annexes → All apps, find system services related to the phone and select Clear cache.
Sometimes, after updating your MIUI firmware, your security settings may get lost, so if you notice that your password request is gone, check the settings again, and you should also consider that dual-symbol phones need to configure each card separately, and their codes may be different.
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The most common mistake users make is ignoring search PUK-Do this proactively to protect yourself from loss of communication.
If the problem is not solved by standard methods, try inserting the SIM card into another phone. If it requires code or does not work there, the problem is precisely in the SIM card or tariff, not in the Xiaomi smartphone.