How to block unknown numbers on Xiaomi: the complete guide

Every year the problem of intrusive calls from scammers and advertising agencies becomes more acute, turning into a real scourge for smartphone owners. Xiaomi, as one of the market leaders, offers built-in protection tools, but their functionality is often hidden from the eyes of the average user or does not work as clearly as you would like. Blocking calls from unknown numbers on devices of this brand is not just a convenience, but a necessary measure of digital hygiene, which allows you to maintain peace of mind and personal data.

MIUI and the new HyperOS have a powerful antivirus and call filtering engine developed in collaboration with international databases. However, standard default settings can skip some unwanted contacts, especially if they use number-definition concealment technologies. Deep setup requires understanding the logic of the system application Security and, in some cases, engaging third-party solutions for maximum effect.

In this article, we will take a look at all the ways you can isolate phone spam, from basic system functions to advanced filtering techniques through engineer codes, and you will learn to create smart rules that will automatically weed out calls from numbers that aren’t saved in your phone book or those whose ID is hidden, allowing you to fully control incoming traffic and forget about annoying beeps at the wrong time.

Use of the built-in Security application

The first and most logical step for any Xiaomi owner should be to explore the capabilities of the pre-installed Security app. This is where the Antivirus section hides the basic functionality of the call blocker, which is often ignored by users. To access the necessary settings, you need to open the application, find the Antispam tab (sometimes hidden in the three-dot menu or setting icon in the upper right corner) and activate the Call Block switch.

Once the basic function is activated, you will see a menu with subtle filtering settings, where you can choose how the system should respond to incoming calls: simply reset them, send them directly to voicemail (if supported by the operator), or simply not emit an audible signal. It is important to understand that turning on this feature does not remove calls from history forever — they can be displayed in the log as missed or blocked, which allows you to check who tried to reach you if necessary.

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For quick activation of the Do Not Disturb mode during important meetings, use the side control panel or set up automatic turn on on schedule in the Watch app.

Special attention should be paid to the Blacklist section within the same menu, which allows you to manually enter specific numbers that are overactive, the system will also offer to connect a cloud database of spam numbers, which will greatly improve the effectiveness of protection. These databases are updated automatically, but require permission to access the network, so make sure that the application has the appropriate rights in the privacy settings section.

Blocking Hidden and Unknown Numbers Through Call Settings

The standard MIUI Phone app has its own settings that run parallel to the security app. To get to the right section, open the call app, click three dots or a gear in the corner of the screen, and select Settings. Here we're interested in "Block numbers" or "Disable calls." This is the menu that implements the feature that most users are interested in: banning calls from unknown numbers.

The function "Block Unknown Numbers" (or "Hide Unknown Numbers") works on the principle of checking the caller ID (Caller ID). If the number is hidden by the sender or not transmitted by the network, the call will be automatically rejected. However, it is worth remembering that this method can be too aggressive: it can block calls from doctors, couriers or emergency services, who for technical reasons may not give their number.

Some versions of the firmware offer a "Block All Inbox" option that works like "On Airplane" for voice only, which is an extreme measure, but it's useful in situations where you need complete silence, and you can set up behavioral patterns, such as allowing calls only from contacts or allowing everything except those on the blacklist, and the flexibility of these settings allows you to adapt the phone to any needs, from full openness to strict "only your own."

Setting up a smart spam filter and advertising calls

Modern versions of HyperOS and recent MIUI updates have intelligent spam detection algorithms that analyze not only the number, but also the frequency of calls, geolocation and complaints of other users. To activate this level of protection, in the application "Security" -> "Antispam" you need to click on the gear settings and select "Filter Options." Here you can enable blocking by category: "Advertising", "Fraud", "Financial Services".

The smart filter works in the background and doesn't require constant user intervention. It checks the incoming number against a global database that is constantly updated. If the number is tagged by thousands of users as spam, your phone just won't ring. This is especially effective against robotic callers that change numbers but stay in the same geographic area or use similar prefixes.

It's worth noting that smart filters require that the application have access to call history and contacts, and without that, you can't do system analysis, and if you value privacy more than spam protection, you can turn it off, but then the blocking efficiency will drop to a manual blacklist.

Use of engineering codes for extended locking

For advanced users who want to access the phone module's hidden features, there are special engineering codes. Entering the ##4636## combination in the call app opens up the testing menu. While direct locking of unknown numbers may not be there explicitly, this menu allows you to check the network status and switch your preferred network type, which sometimes helps if the lock is not working due to problems with the VoLTE signal.

More useful for the blocking topic is the code ##86569726## (Tomato Spam Blocker), which can be active on some regional firmware versions. It opens up a deeper layer of spam database management interface. However, using these codes requires caution: changing random parameters in the engineering menu can lead to unstable operation of the communication module.

⚠️ Note: Entering engineering codes on devices with global firmware (Global) ROM) Often fails because these features are cut out or hidden by localized versions of software for regions in China, India or Russia.

If standard methods don’t work, you can try resetting the network stack through the recovery menu or special ADB commands, but this already requires a connection to a computer. In most cases, the functionality described in the previous sections is enough for the average user, and using engineering codes is more a diagnostic method than a daily tool.

Third-party applications for maximum protection

Xiaomi’s built-in tools are good, but sometimes they’re not enough to fight local spam, especially in specific regions, with specialized apps like Truecaller, Kaspersky Who Calls, or Yandex with Alice (in Definition Mode) coming to the rescue, and these apps have their own, often more complete, databases of numbers that are updated by users in real time.

When you install an app, Android will ask permission to use it as a standard number detector and call handler, which is a requirement: without these rights, the app will not be able to intercept an incoming call and compare the number to the base before the phone rings. Once you set it up, you will get a dual filter: first the MIUI system works, and if it misses the call, a third-party application comes in.

However, this method has a flip side: Third-party determinants require access to all your contacts and call history, which raises privacy issues.Share data about your contacts to third-party servers (even for the sake of spam protection) may not be acceptable for some users.Such applications may consume more battery power by constantly scanning the incoming data stream.

Frequent problems and their solution

Despite the system's cleverness, users may find themselves in a situation where the lock is not working or is not working correctly. Often the problem lies in a conflict of settings: for example, the Security app has a lock on, but the settings of the Phone app itself are priority to skip all calls, and it is also worth checking whether the phone in Do Not Disturb mode with an exception for all contacts, which can block the settings of the blacklist.

Another common problem is the lack of spam database updates: If your phone hasn’t been online in a long time or Google/Xiaomi services are blocked, the databases may become outdated and new fraud numbers will pass through the filter.

⚠️ Note: If the lock has stopped coming after setting up the lock SMS-codes from banks (they often come from short numbers that can be mistaken for spam), be sure to whitelist these numbers or temporarily disable short number filtering.

In rare cases, the operating system itself can cause a crash. If nothing helps, try clearing the Phone and Security app cache through the application management menu. This will not delete your contacts, but will reset temporary files that may have been corrupted.

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A comprehensive approach combining built-in MIUI filter, manual blacklisting and up-to-date databases provides 99% protection against unwanted calls.

FAQ: Frequently Asked Questions