How to block unknown numbers on Xiaomi Redmi Note 9: a complete guide with hidden MIUI chips

Spam calls and messages from unknown numbers have become a scourge of modern times. Xiaomi Redmi Note 9 owners suffer from this as much as others: scammers, intrusive carriers, robots with loan offers - the list goes on forever. Fortunately, MIUI firmware offers several built-in tools to combat this, and third-party applications expand the possibilities of blocking to the limit.

In this article, we’ll look at all the ways you can do it, from basic phone settings to advanced ADB and service-based techniques, how to block not just individual numbers, but entire ranges, how to set up automatic spam filtering via Google Messages, and why the standard Redmi Note 9 blacklist doesn’t work well, and how to get your lock back after resetting, and what to do if calls keep coming in despite all the bans.

Important: instructions are valid for all versions of the Redmi Note 9 (including Note 9 Pro, Note 9S, Note 9T) based on MIUI 12/13/14 and Android 10/11/12. If your phone runs on an older version of the firmware, some menu items may differ - we will warn you about this separately.

1. Standard blacklist in MIUI: how it works and why it does not save from spam

The most obvious way is to blacklist a number through standard settings. However, this method has critical flaws that few people know about. First, it only blocks known numbers, but does not filter new ones. Second, after updating the firmware or resetting the settings, the list can reset. And third, some versions of MIUI ignore the lock for numbers with a changed caller ID (which is how most scammers work).

To add a number to the blacklist:

1. Open the phone application (pipe icon).
2. Go to the Journal section and find the unwanted number.
3. Click on the number, then select ⋮ → Lock down.
4. Confirm the action in the pop-up window.

To manage the entire list of blocked numbers:

• 📱 Go to Settings. → Annexes → Phone. → Number locking.
• 🔍 This shows all the numbers that you've added manually, and you can delete them or edit them.
• ⚙️ Enable the option to Lock Unknown Numbers (if available in your version) MIUI).

Why is it inefficient? Spam centers use thousands of disposable numbers, and manually locking each one is a waste of time, and the standard blacklist in Redmi Note 9 can't analyze the contents of SMS or identify suspicious call patterns (such as mass calls from one number in a short period of time).

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If the number keeps calling after blocking, check if the Do Not Disturb mode is disabled for contacts. Sometimes the settings conflict and the phone misses blocked calls.

2. Automatic locking through Google Messages: a hidden feature for Xiaomi owners

Few people know, but the Google Messages app (which is the default on all Redmi Note 9s with Google services) has a built-in spam filter that works much better than Xiaomi’s standard solution, which analyzes not only numbers but also the contents of SMS, comparing it to a database of known fraudulent messages, and the filter is trained based on user reports around the world.

To enable automatic locking:

1. Open the Messages app (the envelope icon from Google).
2. Slip on the profile avatar in the upper right corner → Message settings.
3. Select Spam Protection → turn on the switch Enable Spam Protection.
4. Activate options: 🔄 Filtering spam messages 🚫 Block spam calls (if available)

Once activated, all suspicious SMS will be placed in the Spam and Lock folder, and numbers marked as fraudulent will be automatically added to the blacklist. Importantly, this feature only works for SMS, but not for calls through the operator - they will require additional settings.

If you don’t have Google Messages installed, download it from the Play Market – it’s completely free and compatible with all versions of the Redmi Note 9. Once installed, make it the default SMS app in your Android settings.

3. Third-party blocking apps: what to choose in 2026

If the built-in tools of MIUI and Google fail, specialized applications come to the rescue, offering advanced features like:

• 🌍 Global spam databases with daily updates.
• 📊 Call statistics and SMS spotting.
• 🔇 Blocking by Keywords in SMS (For example, "credit", "winning", "debt").
• 📵 Create a whitelist for important contacts.

The best apps for Xiaomi Redmi Note 9 in 2026:

Before installing, check the permissions of the application – some request access to the Call Log, SMS and Contacts. This is necessary for work, but if you are embarrassed by transferring data to third parties, choose an offline solution like Blacklist (works only with a local database).

⚠️ Note: Some anti-spam apps conflict with the standard Phone app MIUI. If calls stop working after installation, try turning off battery optimization for the new app in Settings settings → Annexes → Application management → Optimizing the battery.

4. Blocking through operator settings: how to disable spam at the level SIM-map

Many telecom operators (MTS, Beeline, MegaFon, Tele2) offer their own services to block spam. They work at the network level, so they do not depend on the firmware of the phone and do not consume the resources of Redmi Note 9.

• 📶 MTS: Free service "Spam Protection" (activated by the USSD-code *111*789# or in a private office).
• 🔵 Beeline: Paid service "Antispam" (30₽/b) is connected through *110*779#.
• 🟢 MegaFon: "Protection against fraudsters" (free for tariffs with a subscription fee) > 300₽).
• 🟠 Tele2: Automatically locking suspicious numbers (included in the "My Tele2" app").

To connect the protection:

1. Open your operator’s application (or go to your personal account on the website).
2. Find the "Security" or "Spam Protection" section.
3. Activate the service and follow the instructions (SMS confirmation may be required).

The advantage of this method is that locking works even if the phone is turned off or unconnected, but operators do not always quickly update the databases of spammer numbers, so combine this method with others.

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Operators only block voice spam, and SMS filtering will require a separate setting in your personal account or a third-party application.

5. Advanced methods: ADB-commands and hidden settings MIUI

If you're willing to dive into the technical details, you can configure the lock at the system level, which is suitable for advanced users, as it requires working with ADB (Android Debug Bridge) and changing hidden settings.

To start, turn on the developer mode on Redmi Note 9:

1. Go to Settings. → The phone.
2. Tap 7 times on the MIUI version (you will be notified "You became a developer!").
3. Go back to the basic settings and open Additional → for developers.
4. Turn on USB debugging.

Now connect your phone to your computer and execute commands to block unknown numbers:

adb shell settings put global block_unknown_callers 1


adb shell settings put global block_private_callers 1

These teams:

• 🔇 Block all numbers not stored in contacts (block_unknown_callers).
• 🕵️‍♂️ Block hidden numbers (where the caller is located) ID switched off).

To unblock, replace 1 with 0 in commands, and be careful: this method can block important calls (such as from delivery services or banks) if their numbers are not stored in the phone book.

To block SMS via ADB, use:

adb shell content insert --uri content://sms/blocked --bind number:s: "Number"

Where the number is an international phone number (e.g. +79123456789), this method adds the number to the system blacklist, which is not reset after updates.

6.What to do if the lock does not work: diagnosis and alternative solutions

Sometimes even after all the settings, spam calls keep coming in, and the reasons can be different.

• 📵 Numbers use a caller substitution ID (spoofing, and the phone does not recognize them as locked.
• 🔄 Firmware MIUI Reset the settings after the update.
• 🚫 The blocker application conflicts with the standard call.
• 📡 The operator ignores your settings (relevant for virtual operators like Tinkoff Mobile or SberMobil).

Check the following:

⚠️ Note: If you use two of these SIM-In Redmi Note 9, lock settings can only be applied to the main card. SIM, Repeat all the steps for each slot separately.

1. Check the call log: Sometimes blocked numbers show up as missed but without the possibility of a call back. → Journal → ⋮ → Show blocked.
2. Update your firmware: Older versions of MIUI (below 12.5) have lock bugs. Update your phone through Settings → About Phone → System Update.
3. Reset network settings: Go to Settings → SIM-maps and mobile networks → Resetting network settings.This can help if the problem is operator-related.
4. Check Permits: Make sure the blocker app has access to the Call Log and SMS in Settings → Apps → Permissions.

If nothing helps, consider extreme measures:

• 🔄 Reset your phone settings (pre-reverse backup!).
• 📱 Install custom firmware (for example, LineageOS), where the lock is more stable.
• 📞 Change of phone number (if spam becomes unbearable).

FAQ: Frequent questions about locking numbers on Xiaomi Redmi Note 9