SafePhoneHow to Block Unknown and Scam Numbers Automatically on Android
Spam calls and calls from people pretending to be your bank, the police or a delivery driver keep growing. This guide shows you how to block unknown numbers on Android and Samsung phones, from the built-in settings on your phone to blocking scam numbers automatically with SafePhone, including numbers you've never seen before.
Block unknown and scam numbers automatically with SafePhone
Why block unknown numbers?
Spam calls, scam calls and calls impersonating banks or government agencies are increasingly common. These numbers typically:
- Call several times a day, which is a constant nuisance
- Impersonate someone to steal your personal information
- Lure you into tapping malicious links
- Trick you into transferring money or reading out an OTP code
Simply “not answering” isn't enough: you're still disturbed constantly, family members such as children and older adults can still be fooled, and a single call answered by mistake can cost you money. If you're not familiar with scam scripts, read about common scam tactics in 2026 to learn what scammers usually say.
Block unknown numbers with built-in Android and Samsung settings
The default Phone app on Android and Samsung already has a number-blocking feature. The menu names vary by version, but it's usually found here:
- Samsung: open the Phone app → three-dot menu → Settings → Block numbers. Here you can add individual numbers or turn on blocking for unknown (private) callers.
- Android (Google's Phone app): open the Phone app → Settings → Blocked numbers, or turn on spam call filtering under Caller ID & spam.
To also block scam numbers that have never called you before, you need an app with a continuously updated list of scam numbers, like SafePhone.
How to block unknown numbers automatically with SafePhone
SafePhone blocks calls from numbers on its blacklist before your phone rings. To turn this on, you grant the app the Call Screening permission:
- Open the SafePhone app. If you haven't installed it yet, get SafePhone on Google Play.
- Tap the box with title "Call Screener"
- Select "Grant Call Screening Permission".
- Tap “Activate unknown-number shield”. A dialog will appear.
- Select the row with the SafePhone logo and name to set SafePhone as your call screening app.
- Tap the back button to return to the home screen, or close the app and open it again.
Once you're done:
- Calls from blacklisted numbers are blocked automatically, and your phone doesn't ring.
- You can review blocked calls in the call log of your default Phone app.
Want stricter blocking? You can block calls by number prefix such as a particular area code, or block calls from numbers not in your contacts so only people you know can get through.
How does SafePhone identify scam numbers?
SafePhone combines several data sources to build its blacklist, which is how it can block numbers you've never encountered:
Community data
Users report scam and spam numbers; the system aggregates these reports and assesses how dangerous each number is.
Verified number lists
These include numbers that have been reported many times and numbers that make mass automated calls (robocalls).
Behavior analysis
The system watches for unusual call frequency, calls from many numbers with similar prefixes, and calling patterns that resemble spam systems.
Learn more in how SafePhone works.
What is the Call Screening permission?
Call screening is a special Android permission that lets an app check a phone number before you take the call and decide whether to let it ring, silence it, or block it completely.
SafePhone uses this permission to:
- Compare the incoming number against the blacklist.
- Block the call before it bothers you.
- Send an alert to your family's alert channel, if you've set one up; see how to protect your family from scam calls.
Why can't iPhones block calls this way? See call screening permissions on Android and iOS.
Choosing the right way to block unknown numbers
SafePhone has three call-blocking modes. You can use them on their own or combine them:
| Blocking method | Which numbers it blocks | Best for |
|---|---|---|
| Blacklist (this article) | Scam and spam numbers that have been reported or show unusual behavior | Everyone: you still get calls from real delivery drivers and banks |
| Block by number prefix | Numbers matching a prefix, suffix or pattern you choose | People who often get marketing or telesales calls from the same prefix |
| Contacts-only calls | Every number not in your contacts or trusted list | Older parents and children, the groups most vulnerable to scams |
Not sure which app to choose? See our comparison of the best call blocker apps for Android.
Conclusion
Blocking unknown numbers doesn't just spare you from annoyance; it also protects your money and your family's. Every scam number that gets reported also makes the SafePhone community safer.
Turn on the unknown-number shield in just 1 minute
FAQ
Will blocking unknown numbers also block calls from delivery drivers or my bank?
No. Blacklist mode only blocks numbers that have been reported for scams or spam or that show unusual behavior, so you still receive calls from delivery drivers, banks and ordinary unknown callers. If you want to block every number outside your contacts, use contacts-only mode.
How do I block unknown numbers on a Samsung phone?
On Samsung, open the Phone app → Settings → Block numbers to block individual numbers or unknown/private callers. To automatically block scam numbers that have never called you before, install SafePhone and set it as your call screening app.
Can I see the calls that were blocked?
Yes. Calls blocked by SafePhone still appear in the call log of your phone's default Phone app.
Does SafePhone record or listen in on my calls?
No. SafePhone doesn't record calls or access call content; it only processes the incoming phone number to compare it against the blacklist.
Can SafePhone block unknown numbers on iPhone?
SafePhone is currently available on Android. iOS doesn't let apps screen calls before they ring the way Android does, so automatic blocking doesn't fully work on iPhone.