How to block calls from unknown numbers on Xiaomi Redmi 9

Spam calls and intrusive offers have become an epidemic for smartphone owners, especially for low-end and mid-range users such as Xiaomi Redmi 9 owners. The constant interruptions of important work or leisure annoy everyone, and sometimes callers are introduced by bank employees, which is alarming. Fortunately, the MIUI shell installed on your device has powerful built-in tools to filter incoming calls.

In this article, we will discuss how to effectively configure protection against unwanted contacts. You do not need to be an expert in the world of technology to activate a blacklist or connect a database of spammers. We will look at the regular tools of the system that work without installing additional software, and also touch on third-party solutions for more flexible management.

Before we get to the specific steps, it's important to understand that locking can be different: you can prevent calling absolutely everyone whose number is not saved in your notebook, or use smart filters. On Redmi 9, the Antispam feature is built into the system application "Security" and works at the level of a carrier or local database, this provides high efficiency without significant battery consumption.

Use of the built-in "Security" application

The first and most reliable way to protect is to use pre-installed system software. Unlike third-party software, the Security app has deep permissions to the call system, it does not require additional permissions and works steadily even when there is a lack of RAM, which is true for the Redmi 9 model.

To get started, you need to find an icon on your desktop called "Security" and a green shield, and you'll find a lot of options inside the interface, but we're interested in the call filtering section, and it's a powerful engine that analyzes incoming signals before the phone even starts ringing or vibrating.

Inside the menu, you'll see the Antispam item, and you'll click on it, and you'll be taken to the lock control center, and that's where the smart lock is set up, which can detect spam from the database or from the behavior of the subscriber, and the system updates its lists regularly if you allow it to access the Internet.

☑️ Setup of system anti-spam filter

Done: 0 / 4

It's important to note that the settings may vary slightly depending on the version of MIUI. However, the logic remains the same: we search for the lock section and activate the necessary switches. Don't be afraid to experiment with the settings, as all changes are reversible.

Set up a blacklist and filter unknowns

The most radical but effective method is to block all hidden numbers. Often, scammers use special programs to mask their ID, so banning such calls will dramatically reduce the number of alarm calls.

So here you have to select filter mode, so you can block calls only from the numbers that are on your blacklist, or you can turn on "Block all hidden numbers." The second option is especially useful if you don't have calls from people hiding their number. It's a hard filter that guarantees silence.

⚠️ Warning: By including locking all hidden numbers, you risk missing an important call from a doctor, emergency officer or bank if they use secure communication lines.

You can also add specific numbers to the blacklist manually in this section, so if you're constantly concerned about a particular subscriber, just put them on the lock list, and the system automatically resets the caller, and the caller will hear the "busy" or the beep, depending on the operator's settings.

For a more subtle setup, use the option “Block by Keywords” in the SMS-But the main tool for calling is the list of forbidden contacts and hidden numbers. By combining these methods, you create a reliable barrier.

📊 How often do spammers call you?
Every day.
A couple times a week.
Rarely.
Not bothering you.

Blocking through the "Phone" application

An alternative path to settings is directly in the caller. The standard MIUI Dialer app also has lock functionality that duplicates security settings, but may be more convenient for quick list editing. Open the Phone app and click on the three dots in the upper right corner.

In the drop-down menu, select Settings, then go to Lock. Here you will see the same options as in the security application, but in a more compact form, which is convenient when you need to quickly add a number to the blacklist immediately after a missed call.

The Blacklist section displays a log of blocked calls, you can see who tried to reach you, which helps you identify the persistent spammers and, if necessary, put them on a persistent ignore list. SMS-The answer may also be helpful.

You can set up your phone to send a short message to blocked calls, like, "Your number is locked," which isn't always effective against robot callers, but it can scare off live scammers or persistent telemarketers.

What does the caller see when they lock?
The caller usually hears short horns as if the line is busy, or long horns after which the call is reset. The message that the number is blocked does not come to the caller unless you have set up the automatic sending. SMS-response in the lock settings.

Use of third-party applications for protection

If Xiaomi’s built-in tools aren’t enough, the market offers a lot of third-party solutions, apps like Truecaller, Kaspersky Who Calls, or Getcontact have huge databases that are generated by users themselves, and they can identify a spam number even if it’s not on your personal blacklist.

The main advantage of crowdsourcing is that if a thousand people tagged a number as a Taxi or a Credit, you'll know instantly, but installing such applications requires broad permissions, including access to all contacts and calls, which is a matter of personal digital hygiene.

To install, go to Google Play Market, type in the app name and click "Install." After installation, you will need to go through the registration process and give the necessary permissions, and be prepared for the fact that free versions may have ads.

Third-party apps often have more flexible scripting settings, such as allowing calls only during business hours or creating complex rules for different contact groups, which turns your Redmi 9 into a smart filter that skips only the really important ones.

💡

Use Do Not Disturb at night to completely isolate your calls, leaving access only to select contacts from the Favorites list.

Comparison of locking methods on Redmi 9

To make it easier for you to choose the right method, we have prepared a comparison table that will help you weigh the pros and cons of each method of protection from unwanted communication, depending on which is more important to you: maximum security or usability.

MethodEfficiencyDifficulty setting upImpact on the battery
Built-in AntispamTall.Low.Minimum
Manual blacklistMediumLow.Absent.
Third-party annexesVery high.MediumMedium/High
Operator's servicesTall.Low.Absent.

As you can see from the table, MIUI embedded tools are the middle ground, they don't plant a battery or require any extra software, but a combination approach is sometimes required to maximize protection against new scams.

Remember, no method is 100% guaranteed. Bypassing technologies are evolving and spammers are finding new ways, so updating databases and the phone’s operating system itself regularly remains critical.

Services of telecom operators as an additional barrier

And don't forget about your mobile operator, because MTS, Beeline, MegaFon and Tele2 offer paid and free spam protection services, and they work at the network level, meaning that the call simply doesn't reach your smartphone, saving you resources.

To connect such services, it is usually enough to send USSD-For example, many operators have an antispam service that flags or blocks suspicious calls, a network layer of protection that complements the phone's settings.

The advantage of carrier services is that they work even if the phone is off or out of Wi-Fi (although you need mobile internet to update the databases), and they don’t require app installation or request access to your personal data.

However, some advanced features may be subject to subscription fees, check the service plan or terms of service on your operator’s official website, and it often happens that basic protection is free and advanced options cost money.

💡

The combination of the built-in MIUI filter and the operator’s services provides a double level of protection, minimizing the number of spam calls.

Frequently Asked Questions (FAQ)

Will SMS be sent from blocked numbers?
By default, the call lock does not block SMS-To prevent receiving messages from spammers, you need to set up the filter separately. SMS in the application "Security" or "Messages", adding a number to the blacklist for messages.
Does the blocked subscriber know that he is on the blacklist?
No notification of blocking is received, and the call will look like a normal call, but without a response, and may think that you are not picking up, busy, or out of range.
Can I temporarily disable the lock of all unknowns?
Yes, you can go to the Antispam settings at any time and switch the hidden number lock slider to the off position, which allows you to take calls, for example, from couriers who often hide the number.
Are lock settings reset when you update MIUI?
Usually, the blacklist settings and locking rules are saved when you update the system, but after major updates (for example, from MIUI 12 to 13), it is recommended to check the activation status of the filters, as some parameters can be reset to factory values.
Does the blocking of calls affect the speed of the Redmi 9?
Built-in locking has little or no effect on performance. It works at a low system level. However, installing heavy third-party number detectors can consume CPU and RAM resources, as you can see on budget models.