The fastest way to block unidentified calls depends on your phone type
Most phones have a built-in setting that silences calls from numbers not in your contacts. On iPhone, turn on Silence Unknown Callers in Settings > Phone > Silence Unknown Callers. On Android, the method varies by manufacturer — Samsung phones have Block Unknown in Settings > Apps > Phone > Settings > Block Unknown, while Google Pixel phones use Settings > Apps & notifications > Notifications > Advanced > Default notification settings > Block unknown callers.
These built-in tools send unidentified calls straight to voicemail without ringing your phone. They do not delete the calls — you can still see them in your voicemail or call log if you need to check later. This is the simplest option and requires no extra app or subscription.
If your phone's built-in blocking does not work well enough, or if you want more control over which calls get through, third-party apps offer additional filtering. The trade-off is that you are installing another app and sometimes paying a monthly fee.
Key Takeaways
- iPhone users can enable Silence Unknown Callers in the Phone settings to send unidentified calls directly to voicemail.
- Android users should check their phone manufacturer's settings — Samsung and Google Pixel have different locations for blocking unknown numbers.
- Built-in phone blocking is free and does not require an app, but third-party apps offer more detailed filtering if you need it.
- Blocked calls still appear in your voicemail and call history, so you can review them later if necessary.
- Some carriers offer call-blocking services through their own apps or websites, which may work differently than phone settings.
How to use your carrier's call-blocking service
Your phone company may offer its own call-blocking tool, separate from your phone's built-in settings. Verizon offers Call Filter, AT&T offers Call Protect, and T-Mobile offers Scam Shield. These apps are often free but may charge for premium versions that block more types of calls.
To set up your carrier's service, read the app from your phone's app store and sign in with your phone number. Most carrier apps let you choose whether to block, silence, or flag unidentified calls. Some also show you a risk level for incoming calls based on whether the number has been reported as spam.
Carrier services sometimes work better than phone settings alone because they have access to call patterns across millions of customers. However, they also collect data about your calls, which is worth considering if privacy is a concern.
Third-party apps for more detailed call filtering
RoboKiller, Nomorobo, and Truecaller are popular third-party apps that block unidentified and spam calls. These apps use databases of known spam numbers and machine learning to identify suspicious calls. Some offer free versions with basic blocking, while premium versions add features like call recording or detailed spam reports.
The main advantage of third-party apps is customization. You can set different rules for different types of calls — for example, allowing calls from your bank while blocking everything else. You can also see detailed information about why a call was flagged, which helps you decide whether to unblock a number.
The drawback is that these apps require permissions to access your call history and contacts, and they may charge a monthly subscription. Read the privacy policy before installing, especially if you are concerned about how your call data is used.
Manually blocking specific numbers you recognize
If you know the number of a caller you want to block, you can block it directly without waiting for it to call again. On iPhone, open the Phone app, find the number in your recent calls or voicemail, tap the information icon, and select Block this Caller. On Android, open the Phone app, find the number, tap the three dots, and select Block number.
You can also block a number from a text message. On iPhone, swipe left on the message and tap Block. On Android, open the message, tap the three dots, and select Block number. Blocked numbers cannot reach you by call or text, and their messages go to a separate folder.
This method is useful when a specific number keeps calling you, but it does not help with random unidentified calls from different numbers. For those, use your phone's unknown caller blocking or a third-party app.
What happens when you block a call
When you block an unidentified call using your phone's built-in setting, the call goes to voicemail without your phone ringing. The caller hears a message saying the call could not be completed, or they may be sent to voicemail directly. You will see the call in your voicemail or call log, but it will not interrupt you.
If you block a specific number manually, that caller cannot reach you by phone or text. Their calls and messages are stored separately, usually in a blocked list you can access if you change your mind. Unblocking is just as straightforward — find the number in your blocked list and tap unblock.
Blocked calls do not disappear from your phone. You can always review them later to make sure nothing important was missed. This is different from deleting a call, which removes it from your history entirely.
Reducing unidentified calls before they start
The most effective way to get fewer unidentified calls is to limit who has your number. Avoid posting your phone number on public websites, social media, or online forms unless necessary. When you do share your number, use a separate app-based number for online shopping or services you do not fully trust.
If you receive a call from someone claiming to be from your bank or a government agency, hang up and call the official number on your statement or the agency's website. Scammers often spoof official numbers, so calling back directly is the safest way to verify the call was real.
Registering your number on the National Do Not Call Registry does not stop all calls, but it does reduce calls from legitimate telemarketers. You can register at donotcall.gov or by calling 1-888-382-1222 from the phone you want to register. Registration is free and permanent.
Troubleshooting when call blocking is not working
If unidentified calls are still getting through after you turn on blocking, check that the setting is actually enabled. On iPhone, go back to Settings > Phone and confirm Silence Unknown Callers shows as on. On Android, open your Phone app settings and verify the blocking option is turned on.
Some calls may not be truly unidentified — they may have a number that matches a business or service you use, even if you do not recognize it. Your phone's blocking may not catch these. In that case, use your carrier's app or a third-party app, which can identify spam calls even when they have a real-looking number.
If you are using multiple blocking tools at once — your phone's built-in setting plus a carrier app plus a third-party app — they may conflict. Try disabling all but one and see if calls are blocked more reliably. Most people find that one tool is enough.
Frequently Asked Questions
Will the caller know I blocked them?
No. When you block a call, the caller hears a message that the call could not be completed, which is the same message they would hear if your phone was off or you were on another call. They will not receive a notification that you blocked them specifically.
Can I block calls from a specific area code?
Most phone built-in settings do not offer area code blocking, but some third-party apps do. Truecaller and RoboKiller both allow you to block entire area codes or country codes. Keep in mind that legitimate calls sometimes come from unexpected area codes, so this method can accidentally block important calls.
What if I accidentally block someone I know?
You can unblock them at any time. On iPhone, go to Settings > Phone > Blocked Contacts and swipe left on the name to unblock. On Android, open your Phone app, tap the three dots, go to Settings > Blocked numbers, and tap the X next to the number you want to unblock.
Do I need to pay for call blocking?
No. Your phone's built-in blocking is free, and most carrier apps offer free versions. Third-party apps like RoboKiller and Truecaller have free versions with basic blocking, though they offer paid upgrades for additional features.
Will blocking unidentified calls stop robocalls?
Blocking unknown callers will stop most robocalls because they typically come from numbers not in your contacts. However, some robocalls spoof real numbers, so they may not be caught by unknown caller blocking alone. A third-party app that identifies spam patterns is more effective against these calls.