Calls from unknown numbers are one of the most annoying problems of modern smartphones. According to Kaspersky 2023 data, 68% of Android users encounter spam calls at least once a week, and 15% receive them daily. Scammers, marketers, and robo-dialers not only distract you from your business, but also create security risks: phishing schemes, fake “banking services,” and even virus attacks via voice messages.

Fortunately Android offers several built-in tools there are ways to block such calls, from basic phone settings to advanced features of telecom operators. In this article we will analyze all relevant methods for 2026including the hidden capabilities of firmware Samsung One UI, MIUI and clean Android, and also explain why some methods may not work on certain models. You will learn how to set up blocking in 2 minutes, which applications really help, and what to do if a spammer has bypassed all protections.

Why calls from unknown numbers are dangerous: 3 real threats

Many users mistakenly believe that spam calls are just an annoying inconvenience. In fact, they carry specific risks:

  • 🔍 Phishing attacks: Attackers disguise themselves as banks, government agencies or courier companies, luring out personal data. For example, in 2026, more than 12,000 cases of fraud were recorded in Russia through “calls from the bank” asking for a code from an SMS.
  • 💸 Paid connections: One answer to a call from a number like +79xxxxxx890 can activate a paid subscription (cost up to 300 RUB/day). Operators rarely block such numbers automatically.
  • 📱 Viruses through voice messages: In rare cases, spammers send voice messages with hidden commands for vulnerable versions of Android (for example, CVE-2023-20963 in Qualcommchips). It is enough to listen to a message to infect the device.

Interesting fact: according to Truecaller, the top spam numbers for 2026 are led by “pseudo banks” (42% of calls), followed by “loan assistants” (28%) and “technical support” (15%). At the same time, 89% of such numbers use caller ID substitution, which is why they are displayed as “unknown” or “hidden”.

📊 How often do you get calls from unknown numbers?
Daily
Several times a week
Rarely, but aptly
Never

Method 1: Built-in blocking in Android settings (works on 90% of devices)

The fastest and most reliable method is to use built-in Android tools. The instructions are suitable for all smartphones on Android 10 and newer, including Samsung Galaxy, Google Pixel, Xiaomi Redmi and others. The main difference is the layout of the menu items.

Steps for stock Android (for example, Pixel 7 or Motorola Edge):

  1. Open the application Phone (handset icon).
  2. Click on the three dots in the upper right corner → Settings.
  3. Select Blocking numbers and spam (or Blocked numbers on some firmware).
  4. Activate the switch Unknown numbers or Hidden numbers.
  5. Additionally enable the option Spam filtering (if available).

For Samsung One UI (for example, Galaxy S23):

  1. Run Phone → ⋮ → Settings.
  2. Go to Blocking numbers.
  3. Enable Block unknown numbers.
  4. Activate Show notifications about blocked callsto see who tried to call.

Is the "Unknown numbers" switch activated?

Is spam filtering enabled (if available)?

Have exceptions been checked for important contacts?

Are the settings synchronized with your Google account (for backup)?-->

Important: On some firmware (for example, ColorOS from Oppo/Realme) blocking unknown numbers may conflict with the Smart Call feature. If calls continue to come in after setting up, disable the option in your phone settings Call optimization or AI service calls.

💡

If you have a dual-SIM smartphone, set up blocking separately for each SIM card. Some operators (for example, MTS or Beeline) reset these settings after updating the firmware.

Method 2: Blocking through a telecom operator (free for subscribers)

Mobile operators offer their own anti-spam services that work at the network level - this means that calls are blocked before they even reach your phone. The service is usually free, but requires activation.

Operator Connection method USSD command Features
MTS Send SMS with text STOP SPAM to number 111 *111*789# Blocks 85% of spam numbers, but does not work with international calls
Beeline Dial *110*789# and follow the instructions *110*789# Additionally filters SMS spam, but can block legitimate mailings
MegaFon Send an empty SMS to 0001 *105*789# The most aggressive filtering, but sometimes blocks calls from taxi/delivery
Tele2 Dial *220*1# and select the “Protection against spam” option *220*1# Works only for Russian numbers, there is no protection against “gray” SIM cards

⚠️ Attention: Operator services may conflict with blocking at the Android level. If, after activation, important calls (for example, from couriers) stop coming, check Call log → Blocked in the application Phone and add the necessary numbers to exceptions.

Also keep in mind that operators update their databases of spam numbers with a delay of 1-3 days. If you receive a call from a new fraudulent number, it may be filtered. In such cases, combine this method with blocking at the smartphone level.

Method 3: Applications for blocking spam (Top-3 in terms of efficiency)

If the built-in tools do not cope, you should install a specialized application. We tested 12 popular solutions and selected the three most effective:

  • 🛡️ Truecaller:
    • Base of spam numbers: 500 million+ records (updated every 12 hours).
    • Functions: blocking calls/SMS, identification of unknown numbers, recording conversations (on some firmware).
    • Cons: requires access to contacts, sometimes displays advertising.
  • 🔍 Hiya (former Whitepages):
    • It specializes in fraudulent numbers from the USA/Europe, but it also works well in Russia.
    • There is a “Reverse Search” function that shows who owns the number.
    • Cons: the free version limits the number of blockings (up to 100/month).
  • 📵 Should I Answer?:
    • Minimalistic interface, no advertising, completely offline database.
    • Allows you to create your own blocking rules (for example, by geolocation of the number).
    • Cons: smaller database of spam numbers compared to Truecaller.

🔹 How to set up Truecaller for maximum protection:

  1. Install the application from Google Play (avoid third-party sources!).
  2. When you first start, allow access to The Journal calls and Contacts.
  3. Go to Settings → Blocking and turn on:
    • Block spam calls
    • Block hidden numbers
    • Block numbers from the black list
  • In section Spam filter select level High.
    • Why does Truecaller ask for access to contacts?

    The application uses crowdsourcing: when users mark a number as spam, this information is added to the general database. Contacts access is needed to show the names of callers from your address book. You can disable this feature in settings, but then Truecaller will not be able to identify legitimate numbers (for example, colleagues or friends).

    ⚠️ Attention: Some blocking applications (for example Call Blocker or Blacklistcan intercept SMS filtering spam. This creates the risk of data leakage if the application turns out to be fake. Always check the developer (official applications are published under verified accounts) and read reviews for the last 3 months.

    Method 4: Blocking via Google Messages (for SMS and calls)

    If you use Google Messages as your main SMS application, it has a built-in spam filter that works for calls as well. This method is especially useful for owners Google Pixel, but is also suitable for other devices with installed Messages.

    Instructions:

    1. Open Google Messages.
    2. Click on your avatar in the upper right corner → Settings messages.
    3. Select Spam and fraud protection.
    4. Enable options:
      • Filter spam messages
      • Show fraud alerts
      • Block spam calls (if available)
  • Go back to the main settings and activate Call verification (shows the reason why the number is marked as spam).

    • 🔹 Advantages of this method:

    • Works at the level of Google services, so blocking is applied even if the number is not blacklisted on your phone.
    • Integrated with Google Duet (video calls) and Google Fi (virtual operator).
    • Updates the database of spam numbers in real time.

    ⚠️ Attention: If you use Samsung Messages or another third-party SMS application, this method will not work. Also Google Messages does not block calls from international numbers unless they are marked as spam by other users.

    Method 5: Manually adding numbers to the blacklist

    If a specific number continues to call you despite everything filters, add it to the blacklist manually. This is guaranteed to block all communication attempts, including SMS.

    🔹 Instructions for standard Android:

    1. Open Phone → Call log.
    2. Find the desired number and click on it.
    3. Select Block or Add to blacklist (on some firmware - Mark as spam).
    4. Confirm the action.

    🔹 For Samsung One UI:

    1. Go to Phone → ⋮ → Settings → Blocking numbers.
    2. Click Add number and enter it manually or select from the log.
    3. Activate the option Block messagesif you need to block SMS as well.

    🔹 For Xiaomi (MIUI):

    1. Open Security → Block numbers.
    2. Select Black list → Add.
    3. Specify the number and type of blocking (Calls + SMS or only Calls).

    💡 Tip: If the spammer uses different numbers with the same prefix (for example, +7912xxx), you can block an entire range. To do this, manually add a number with the symbol * instead of the last digits (for example, +7912***This does not work on all firmwares, but is supported in MIUI And ColorOS.

    Method 6: Using Do Not Disturb mode with exceptions

    If you need maximum silencebut don’t want to miss important calls, set up the mode Do not disturb (DND) with exceptions for known contacts. This method blocks all unknown calls, but allows selected numbers.

    🔹 How to set it up:

    1. Go to Settings → Sound → Do Not Disturb.
    2. Turn on the mode Do Not Disturb.
    3. Click People and select Contacts only or Favorite contacts.
    4. Go back and activate Allow repeated calls (if someone calls twice within 15 minutes, the call will go through).
    5. In the section Calls disable Unknown numbers.

    ⚠️ Attention: In the mode Do not disturb notifications about missed calls will not be received from blocked numbers. If it is important for you to see who tried to call (for example, to track scammers), use instead Method 1 (built-in blocking).

    🔹 Additional settings for advanced users:

    • In Do not disturb you can set Schedule (for example, block unknown calls at night).
    • On Samsung in DND mode there is an option Ruleswhere you can create separate profiles for work/home/sleep.
    • On Xiaomi in Settings → Memory and performance → Sleep mode you can link call blocking to lights out time.

    Method 7: Advanced methods (for root users and the tech savvy)

    If you're ready to dive into the technical details, these methods will give you the answer. 100% blocking even the most persistent spammers ⚠️ Attention: inexperienced users are better off skipping this section - incorrect actions can cause the phone to crash.

    🔹 Method 1: Blocking via ADB (without root)

    Using Android Debug Bridge you can block unknown numbers at the system level:

    adb shell settings put global block_unknown_callers 1

    To unblock:

    adb shell settings put global block_unknown_callers 0

    🔹 Method 2: Editing a file build.prop (requires root)

    Add to the file /system/build.prop the line:

    ro.telephony.call_blocking_enabled=true

    Then reboot the device. This method activates hidden locking functions on some firmwares (for example, on Sony Xperia or Nokia).

    🔹 Method 3: Using the Xposed Framework (for advanced users)

    Module XPrivacyLua or Call Blocker for Xposed allows you to create complex blocking rules, including:

    • Blocking by geolocation of the number (for example, all calls from Nigeria).
    • Filtering by keywords in caller ID (for example, “bank”, “credit”).
    • Automatic redirection of spam calls to voicemail.

    ⚠️ Attention: Use Xposed or modification of system files may lead to:

    • Loss of warranty on the device.
    • Unstable operation of the phone (random reboots, call errors).
    • Problems with OS updates (failure to install OTA packages).
    💡

    Before using advanced methods, make a backup copy of your data via Settings → System → Backup or using TWRP (for root users).

    What to do if the spammer has bypassed all protections?

    Even after setting up all the filters, some particularly persistent scammers may call. Here's what to do in such cases:

    1. Check the call log for number spoofing:
      • Open Phone → Log → ⋮ → Settings → Call history.
      • Find a suspicious number and look at it details.
      • If a different number is indicated in the details (for example, a call allegedly from Sberbank, but in the details +234xxxx), this is 100% substitution.
    2. Complain to the operator:
      • Send an SMS with the text Spam [phone number] to the short number of your operator (u MTS — 1234, u Beeline — 363).
      • Or call support and report a fraudulent number.
    3. Add the number to the global spam database:
      • V Truecaller: open the number → Complain → Fraud.
      • B Yandex.Phone: click on the number → This is spam.
    4. File a complaint to Roskomnadzor:
      • If the spammer introduces himself as a bank or government agency, fill out the form on the website Roskomnadzor (section "Illegal calls").
      • Attach screenshots of the log calls and, if available, recording of the conversation.

    💡 Advice: If you often receive calls from international numbers, install the application Call Control —it specializes in blocking foreign spam and supports geo-filtering (you can block all calls from specific countries).

    FAQ: Frequently asked questions about blocking unknown numbers

    Can I block all incoming calls except selected contacts?

    Yes, for this:

    1. Activate the mode Do not disturb (Settings → Sound → Do not disturb).
    2. In the mode settings, select People → Only selected contacts.
    3. Disable the option Unknown numbers in the section Calls.

    Now only calls from contacts marked with an asterisk in the address book will go through.

    Why, after blocking unknown numbers, do I not see missed calls from them?

    It depends on firmware:

    • On pure Android (Pixel, Motorola) blocked calls are not displayed in the log.
    • On Samsung they appear in the log with a mark Blocked.
    • On Xiaomi you need to enable the option Show blocked in the blocking settings.

    If it is important for you to see all missed calls, use application Truecaller —it keeps a separate log of blocking.

    How to block SMS from unknown numbers?

    To block SMS:

    1. V Google Messages: Settings → Spam and protection → Enable spam filter.
    2. On Samsung: Messages → ⋮ → Settings → Blocking numbers and spam.
    3. On Xiaomi: Security → Blocking numbers → Block messages.

    To completely block unknown SMS, use the application SMS Blocker (requires permission to read messages).

    Will blocking work if I have two SIM cards?

    Yes, but the settings will have to be duplicated for each SIM:

    • On Android 12+ locking applies to all SIMs by default.
    • On Samsung i Xiaomi you need to select a SIM card in the blocking settings.
    • If you use Truecaller, it blocks calls to all SIMs automatically.

    ⚠️ Attention: On some dual-SIM phones (for example, Realme Narzo), blocking unknown numbers only works for the main SIM. Check this manually.

    Is it possible to return a blocked number? to the call log?

    Depends on the firmware:

    • Pure Android: No, blocked calls are not saved.
    • Samsung/Xiaomi: Yes, they are displayed in the log with a mark Blocked.
    • Workaround: Install Truecaller —it keeps a separate blocking log.

    If you need to recover the history of blocked calls, try exporting the log via Settings → System → Backup (if the function was enabled before blocking).