The vast majority of smartphone owners are facing intrusive calls, and Xiaomi Redmi users are no exception, especially annoyed when the screen displays the words “Unknown Number” or “Hidden Number”, which makes it impossible to add contact to the blacklist by standard methods. Owners of the Redmi 9 Pro often look for ways to effectively cut off this flow of digital garbage without missing an important call from a doctor or delivery service.
The modern Android-based MIUI operating system provides powerful tools for filtering incoming traffic, but many features are hidden in the depths of the menu or require the correct initial setup. In this article, we will detail how to configure the locking of hidden numbers on your device using built-in system tools, mobile codes and specialized applications. You will learn to create a reliable spam shield that does not require constant user intervention.
Before we get to the complex manipulations, it is worth noting that the effectiveness of the method depends on the source of the call. If spammers use special programs to change the number (spoofing), even blocking the "unknown" may not help, since it will look like a regular but someone else's number to the system. However, setting up the filtering of calls at the system or SIM card level allows you to cut off up to 90% of unwanted noise, saving your nervous system and time.
Use of the built-in MIUI call filter
The first and most logical step for the owner of Xiaomi Redmi 9 Pro is to activate the built-in protection mechanism. MIUI has its own antivirus and anti-spam engine developed in collaboration with Tencent (in global versions) or 360 Security (in Chinese firmware), which is able to analyze incoming calls and automatically block those that are labeled by other users as spam, or hide their ID.
To activate this feature, you need to open the standard Phone app (green handset) and go to settings, and it's important not to confuse the settings of the application itself with the general settings of the system. We're interested in the call management menu, where the Antispam item is hidden, and this is where the basic magnesium is going to sort incoming connections.
Inside the anti-spam menu, you'll see a "Block Unknown Numbers" switch, which activates any call that doesn't have a numeric ID (i.e., from a hidden number) will be automatically reset by the system before your phone makes a call, the subscriber will hear a beep or a lesson message, and you will receive a notification of a blocked call in the log.
☑️ Setup of the built-in filter
Note that MIUI algorithms are updated periodically and the database of the spam numbers is replenished, but for maximum efficiency, it is recommended to also enable synchronization with the cloud base, if this option is available in your area, which will allow the phone to know about new scams almost instantly.
Setup of blocking through the services of mobile operators
If Xiaomi’s built-in tools are not enough, or you want to be guaranteed to cut off hidden numbers at the network level, it is worth turning to the services of your mobile operator. The largest operators (the “Big Four” in Russia and analogues in the CIS) provide services such as “Anti-Detector” or “Hidden Number Lock” that operate regardless of the model of your phone, whether it is Redmi 9 Pro or any other device.
The essence of the method is that the operator switch does not miss a call to your SIM card unless the caller's number is broadcast to the network, which is the most reliable way, since the call simply does not reach your device, without consuming its resource and without distracting you. Activation of the service usually occurs through USSD-team-room.
- 📞 MTS: Blacklist allows you to block specific numbers, but hidden ones often require the connection of the number detector option with a reverse setting.
- 📞 MegaFon: The Anti-AON or Blacklist service is configured via an app or website, allowing you to create rules for anonymous people.
- 📞 Beeline: The Black List service has a function to block all hidden numbers, which is ideal for our task.
- 📞 Tele2: Offers the option “Black list”, where you can add masks or configure the blocking of anonymous people through profile settings.
Before connecting, carefully examine your carrier’s rates to avoid unexpected write-offs.In some cases, activation can take up to 24 hours.
⚠️ Note: When using a network lock, you may miss an important call from emergency or social workers who, by regulation, sometimes hide their number.
Application of third-party applications for filtering
When standard Android and MIUI tools fail, specialized applications from the Google Play Store come to the rescue, with Truecaller, NumBuster and Kaspersky Who Calls leading the niche, and they have huge numbers databases that are replenished by users around the world.
The principle of such applications on Xiaomi Redmi 9 Pro is to intercept an incoming call. The application checks the number against the database and, if the number is marked as “Spam”, “Sales” or “Fraudsters”, automatically resets the call. To work with hidden numbers in the settings of such applications, there is often a separate toggle “Block hidden / private numbers”.
But installing third-party software requires broad permissions, and the application needs access to your contacts, call logs, and sometimes even SMS, to synchronize databases and determine the context of the call, and the user has to decide whether they are willing to sacrifice some privacy for the sake of silence.
Risks of using third-party determinants
In addition, such applications can consume additional battery power and RAM, which on the Redmi 9 Pro model with its not-the-newest processor can be noticeable.
Manual lock through Android system codes
There is a lesser known but effective way of blocking that works at the GSM protocol level: using dialing codes that send a command directly to your Xiaomi communication module, which is good because it does not require additional software installation and works even in safe mode.
Special sequences can be used to activate Do Not Disturb mode or redirect all hidden calls. However, there is no universal code for all operators, and often requires the use of a forwarding command to a number that does not exist, or to voicemail and then reset.
For example, the command **61* voicemail mail# can be used to set up redirects during a session, but hidden numbers often require activation of the service from the operator via the USSD. However, some versions of MIUI firmware operate a direct ban through the engineering menu, although access is limited.
| Type of lockdown | Activation method | Efficiency | Difficulty |
|---|---|---|---|
| Built-in MIUI filter | Phone settings | Tall. | Low. |
| Operator's services | USSD / Personal Account | Maximum | Medium |
| Annexes (Truecaller) | Google Play | Medium/High | Low. |
| Do Not Disturb mode | Notification curtain | Low (blocks everyone) | Low. |
Using codes requires care. A single-digit error can lead to activation of a paid service or redirecting your calls to someone else's number. Always double-check the entered data before pressing the call button.
Setting up the “Do Not Disturb” mode as a temporary solution
If you need silence right now and you don’t want to get your filter settings sorted out, the ideal solution is Do Not Disturb (DND) mode. On the Xiaomi Redmi 9 Pro, it’s very flexible and allows you to create exceptions, which is critical to keep a call from loved ones.
You can activate this mode through the notification curtain or in the Sound and Vibration settings. The main feature is the exception setting. You can allow repeated calls (if the same number rings a second time in 3 minutes, the call will pass) or allow calls only from the favorite contacts list.
This is great for night time or important meetings, but as a constant measure to combat hidden numbers, it is inconvenient, requiring manual switching on and off, but it is a feature that every Android smartphone owner needs to know.
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Tip: Set up Do Not Disturb mode automatically on schedule (e.g. 23:00 to 07:00) to save you from late-night spam without the risk of sleeping a really important call if you add family contacts to the exceptions.
In the mode settings, you can also prevent notifications from appearing on a locked screen, which adds another layer of privacy: no one outsider will see who is calling or texting you while the phone is in this mode.
Analysis and prevention of block circumvention
Spambots and telemarketers are constantly improving, and they know that there are locking features on Xiaomi and Android in general, so they change tactics, and instead of hiding the number, they can use pools of local numbers that look like regular city or mobile calls.
In this case, blocking the unknowns will not help, relying on heuristic analysis provided by applications like Google Phone (which can be installed instead of a standard call) or the aforementioned Truecaller, which flag suspicious numbers in red before they respond.
Also, be careful about so-called "missing" calls from unknown numbers. Never return calls to such numbers. This can be a toll line or a way to check your number's activity for further attack.
⚠️ Note: Never report codes from SMS, Even if the caller is a banker or a police officer, real employees never ask for confirmation codes, locking the number won't protect you from social engineering if you pick up the phone yourself.
Regularly update the antivirus database in your phone and the application itself to identify the number. Old databases simply do not know about the new numbers of scammers that appear every day.
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Comprehensive approach: The maximum protection is provided by the combination of the built-in MIUI filter (for basic locking) and the operator service (for network level cut-off).