How to permanently lock unknown numbers on Xiaomi Redmi 9: from standard tools to secret chips

Spam calls and messages from unknown numbers have become a real scourge of modern smartphones. Owners of Xiaomi Redmi 9 are no exception: every day a call from Mosenergosbyt, "bank security services" or simply unfamiliar subscribers with the code +79xxxxxx can appear on the screen. But unlike the iPhone, where locking is limited to standard iOS, MIUI firmware offers a whole arsenal of tools - from built-in functions to hidden settings of the engineering menu.

In this article, we will discuss 5 working ways to lock unknown numbers on Redmi 9 (including Redmi 9A/9C/9T models), taking into account the features of different versions of MIUI - from MIUI 12 to MIUI 14.

• 📱 Set up automatic locking via the standard Phone app
• 🔒 Use the Blacklist with Extended Filters
• 🤖 Activate hidden lock function by number prefixes
• 🛡️ Install third-party artificial intelligence apps to recognize spam
• ⚙️ Change system settings to lock at operator level

Important: some methods require root rights or developer mode activation, and we've marked these cases with special warnings, and at the end of the article, you'll find an FAQ that answers common questions, such as why locking doesn't work on double-sims or how to recover randomly deleted numbers from a blacklist.

1. Standard lock through the application "Phone"

The easiest way is to use the built-in MIUI tools. They do not require additional applications to be installed and work on all versions of Redmi 9, including the budget versions 9A and 9C.

Instructions:

1. Open the Phone app (the phone icon on the home screen).
2. Go to the tab "Journal" (bottom of the screen).
3. Find the unknown number you want to block and tap it.
4. In the window that opens, press three dots ("⋮") in the upper right corner.
5. Select the "Block Number" option and confirm the action.

🔹 Features of the method:

• ✅ Works without internet and additional permits
• ✅ Blocks both calls and SMS from selected number
• ❌ Does not block numbers with spoofed data
• ❌ You need to manually add each spam number.

If you're tired of making constant calls from the same number (such as collectors or scammers), this method is perfect, but it's not effective for mass blocking of unknown subscribers, you have to spend time on each contact separately.

💡

To quickly find a number in the magazine, use the search bar at the top of the screen. Type the first 3-4 digits and the system will show all the matches.

2.Setting up the "Black List" with extended filters

MIUI has a hidden Blacklist section that allows you to not only block individual numbers, but also set rules for unknown subscribers, a method that works if you are flooded with calls from different numbers but with the same prefix (for example, +7926xxxx or +7495xxx).

How to set up:

1. Open Settings → Applications → Phone → Blacklist.
2. Slip the "+" icon in the upper right corner.
3. Select "Add number manually".
4. In the input field, specify: 📞 Full number (e.g., +79123456789) – to lock a particular subscriber 🔢 Prefix (e.g., +7926) – to lock all numbers with this beginning

"Done."

🔹 Additional settings:

• 🔄 Enable the "Block Unknown Numbers" option, which will block all incoming identifiers from hidden or unknown identifiers.
• 📵 Activate Block Messages if spam is coming and through SMS.
• 🔍 Use the Lock Log (in the same section) to see how many calls have been stopped.

Important: Prefix locks can affect legitimate numbers (e.g., delivery services or banks) and check if the organizations you want are using the same number beginnings before setting up.

3. Hidden number mask locking function (only for MIUI 12.5+)

Starting with MIUI 12.5, Xiaomi’s firmware has a hidden mask lock feature that allows you to create templates to automatically lock numbers that fit a specific format, for example, you can block all numbers starting at +375 (Belarus) or +380 (Ukraine) if you get caught by international spammers.

How to activate:

1. Open the phone app.
2. Go to Settings → Block and Identification → Blocking Rules.
3. Turn on the mask lock switch.
4. Click Add Mask and enter the template: 🌍 To block international numbers: +* 📱 To lock numbers with a specific prefix: +7926* 🔢 To lock numbers with repeating numbers: 111 or 2222

Save the changes.

⚠️ Warning: This feature may conflict with some SIM- cards of Tele2 and Iota operators. If important calls stop coming after setting up, turn off the masks and use another method.

Example of effective masks for blocking:

• 🚫 +7495* – all Moscow rooms (if you get annoyed by local spammers)
• 🚫 +7800* – toll-free numbers (often used by fraudsters)
• 🚫 # – Numbers with # (sometimes found in spam mailings)

Make sure important numbers don't fall under the mask | Back up the blacklist | Check the lock on the test number | Turn off the masks if important calls are missing

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4. Third-party applications to block spam

If the built-in MIUI tools fail, third-party apps will come to the rescue, using real-time spam databases that often identify scammers before you even answer a call.

Top.-3 supplant 9:

🔹 How to set up Truecaller on Redmi 9:

1. Download the app from Google Play.
2. Register (you can use Google or phone number).
3. In the settings, enable: 🛡️ "Spam Blocking" 📵 "Blocking SMS" 🔍 "Detection of Unknown Numbers"

"Blacklist."

⚠️ Warning: Apps like Truecaller collect data about your contacts and calls, if you're confused, use it offline (no cloud sync) or opt for built-in tools MIUI.

💡

Third-party apps are more efficient than built-in tools, but require more rights and can affect the autonomy of the smartphone (Truecaller consumes up to 5% of the charge per day).

5. Blocking at the operator level (for MTS, Beeline, MegaFon, Tele2)

If spam calls are at the SIM- level, they can be blocked by the mobile operator, which is independent of the phone’s firmware and works even if you reset the Redmi 9 before the factory settings.

Instructions for popular operators:

• 📶 MTS: Send SMS with the text of Block 79123456789 to 111 (where 79123456789 is spam number). To block all unknowns: Block NEIZV.
• 📶 Beeline: Call *110*79123456789# or send USSD- a request *110*3# to block hidden numbers.
• 📶 MegaFon: Use the command *130*1*79123456789# or your personal account on the site.
• 📶 Tele2: send SMS Block 79123456789 to 707.

🔹 Pros of the method:

• ✅ Works on any phone (even if you swap the Redmi 9 for another smartphone)
• ✅ Locks calls before they reach your device
• ✅ No need to install applications

🔹 Cons:

• ❌ Not all operators block SMS
• ❌ Fees may be charged (for example, Beeline has 3 rubles per room)
• ❌ List of blocked numbers resets when SIM- card is changed

If you change operators frequently or use two SIM- cards, combine this method with built-in MIUI tools for maximum protection.

6. Additional measures: engineering menu and root access

For advanced users willing to risk system stability, there are ways to lock at the level of modified firmware or engineering menus, which require root rights or developer mode activation.

🔧 Method 1: Engineering menu (no root)

1. Activate Developer Mode: Go to Settings → About Phone and tap on MIUI Version 7 times.
2. Return to Settings → Additional → For developers and enable “Debugging by USB”.
3. Open the Phone app and enter the code ##4636##.
4. Go to the “Phone Information” section and select “Network settings”.
5. Find the option “Block inbox” and add numbers or prefixes.

🔧 Method 2: Root-access applications (power users only)

If you have Magisk or another root tool installed, try:

• 🛠️ Xposed Framework + Blacklist module allows you to block calls at the system level.
• 🛠️ AFWall+ is a firewall that can block connections from spam numbers.

⚠️ Warning: Incorrect actions on the engineering menu or with root rights can lead to:

• 🔄 I'll reset to factory settings
• 📵 Loss of communication with the operator's network
• 🔋 Accelerated battery discharge

FAQ: Frequent questions about room locks on Redmi 9