The problem of intrusive calls from unknown and hidden numbers is familiar to many smartphone owners. Owners of Xiaomi devices, in particular the popular Redmi Note 9 model, often face a situation where the caller hides his ID, making it impossible to add it to the blacklist by standard means, which causes irritation and disturbs the peace, especially if calls come from spammers or collectors.
Fortunately, Android, in conjunction with the MIUI, offers several effective ways to solve this problem: you can use built-in locking functions, special codes from a mobile operator or third-party applications to filter calls. It is important to understand that you can not completely “repeal” the definition of a number at the network level, but you have the right to prevent the phone from accepting such calls.
In this article, we’ll take a look at all the methods available, from simple menu settings to more complex code manipulation. Blocking anonymous calls is an important step toward digital hygiene that will keep you focused and nervous system in order. Let’s take a look at what tools are available to Redmi Note 9 owners right now.
Use of the built-in Antispam function in MIUI
The first and most logical step for the owner of the Xiaomi smartphone is to check the built-in protections. The MIUI shell is famous for its deep functionality, and the tools for combating spam are implemented very competently. Unlike “pure” Android, it does not always require the installation of additional software.
To activate the basic security, you need to open the standard Security app, which is a system utility that usually has a green shield icon, and inside the menu you need to find the section that blocks calls, and the path may vary slightly depending on the firmware version, but the logic remains the same.
The built-in filter is able to analyze incoming calls in real time, it checks the number against databases and can block not only obvious spam, but also attempts to hide the number, if this option is supported by your version of the software and region.
- 📱 Open the Security app on the home screen.
- 🛡️ Go to the “Antispam” or “Blocking” section».
- ⚙️ Click on the settings icon (cog) in the corner of the screen.
- 🚫 Find the option “Block Unknown Numbers” or similar.
Note that the functionality may vary: in some regions, MIUI requires an Internet connection to update spammer databases. If the standard means to block a hidden number (No Caller ID) is not possible, move to the following methods, which are more versatile.
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Regularly update the databases in the Security app to ensure that the protection works as effectively as possible against new spammer schemes.
Blocking through the standard application “Phone”
The second method does not require searching for additional menus, since everything you need is in the application for calls. The dialing interface in Redmi Note 9 has hidden features that are often ignored by users. This is where you can customize the behavior of a smartphone when a call is received without an ID.
Open the Phone app and find the settings menu, which is usually hidden behind three dots in the top right corner or the gear icon, and you're interested in the lock settings or call ban section, and these are the key switches to control incoming traffic.
Important: on some versions of Android, the option to block hidden numbers may be hidden in the deep menu or not if the carrier does not transmit the corresponding signal.
Settings → Block → Blacklist → Blacklist settingsThe blacklist menu often features a "Block Calls from Unknown Numbers" switch.Activating this feature causes the phone to reset any call where Caller ID is not defined.This is a crude but effective method that guarantees silence, but can miss an important call from a doctor or delivery service if they mistakenly hide the number.
☑️ Checking call settings
Application USSD-codes
The most reliable way that works at the operator network level is to use special commands. Telecom operators (MTS, Beeline, MegaFon, Tele2, etc.) provide services to block anonymous calls, this works regardless of the model of your smartphone, whether it is a Redmi Note 9 or any other Android phone.
The idea is to send a short request to the network, and after activating the service, the operator will turn down calls where the subscriber number is hidden, and you don't even have to keep the phone on to do this, because the filtering is done on the cell tower side.
Below is a table with codes for major Russian operators. Please note that some services may be paid or require pre-activation through your personal account.
| Operator. | USSD-activation | Status of service |
|---|---|---|
| MTS | *111*442# | Paid (usually) |
| Beeline | *110*771# | Free of charge. |
| Megaphone | *105*11# | Paid. |
| Tele2 | *129*11# | Free of charge. |
After entering the code, you will receive SMS-Activation notification: Operator-side locking is a hard-to-concrete method that cannot be bypassed by software failures on your phone. If the codes don't work, check the current information in the salon or on your provider's website.
What if the code doesn't work?
Third-party applications for call filtering
If the built-in MIUI and operator codes don’t work, Google Play apps come to the rescue, with more flexible algorithms and often their own number databases updated by the community.
One of the leaders in this niche is Truecaller, which can detect and block spam, and has a hidden number lock feature, and once installed, the app will ask for permission to manage calls, which is a necessary step for the filter to work.
In the application settings, you need to find the “Block” section and activate the “Block Hidden Numbers” slider. The application algorithm will analyze the incoming signal and, if it does not have an ID, reset the call before the phone starts ringing.
- 📥 Download the number-defining application (Truecaller, GetContact, Yandex).
- 🔐 Give the necessary permissions to access contacts and calls.
- 🗑️ In the lock menu, enable the option “Hidden numbers».
- ✅ Check the work by asking someone to call you from a hidden number.
⚠️ Note: By installing third-party number detectors, you agree to transfer your contacts to the developer servers.
Other apps, such as Should I Answer?, also offer powerful filtering tools without necessarily uploading a phone book to the cloud, which is important for privacy-conscious users.
Setting up the “Do Not Disturb” mode as an alternative
An interesting workaround to block unwanted calls, including hidden ones, is using Do Not Disturb (DND) mode. In Redmi Note 9, this mode is configured very flexibly and allows you to create exceptions. You can set the phone so that it only skips calls from contacts in your phone book.
Because a hidden number by definition cannot be written in your contact book (you don’t know whose number it is), such calls will automatically be blocked or simply won’t make a sound while the mode is active.
To activate, go to Settings → Sound and vibration → Do not disturb. Under Allow Calls, select Contacts Only. Now the phone will ignore everyone who is not on your friends and colleagues list.
Settings → Sound and vibration → Do not disturb → Allow calls → Contacts only💡
Do Not Disturb mode with Contacts Only filter is an ideal way to ignore hidden numbers without installing third-party programs and activating paid operator services.
But there's a downside to this method: you can miss an important call from a courier, taxi, or doctor if their number isn't stored in your phone's memory, so it's best to use it during periods when you need absolute silence, rather than as a permanent solution.