The fastest way to block unknown numbers

Open Settings on your iPhone, then go to Phone > Call Blocking & Identification. Turn on Silence Unknown Callers. This sends any call from a number not in your contacts, recent calls, or Siri suggestions straight to voicemail without ringing your phone.

This is the simplest option if you want unknown calls gone immediately. The calls still arrive as voicemails, so you can listen later if you want. Nothing is deleted — you can find the voicemails in the Phone app under the Voicemail tab.

One thing to know: legitimate callers you've never spoken to before — a doctor's office calling about an appointment, a delivery driver, a callback from a job interview — will also go to voicemail. You won't hear the phone ring. If you need to catch calls from people you don't know yet, this method isn't the right fit.

Key Takeaways

  • Silence Unknown Callers in Settings sends all unknown numbers to voicemail without ringing your phone, and works immediately with no setup.
  • You can block specific numbers one at a time by opening a call or message, tapping the info icon, and selecting Block this Caller.
  • Third-party apps like Nomorobo, RoboKiller, and Truecaller use spam databases to filter calls before they reach you, and let you see who called.
  • Legitimate callers you haven't saved — doctors, delivery services, callbacks — will be silenced too if you use the unknown caller filter.
  • Blocked callers can still leave voicemails, but their calls won't ring through and won't show notifications.

Block individual numbers manually

If you want to keep hearing from unknown callers but block specific spam numbers, block them one at a time. Open the Phone app, find the number you want to block in your recent calls, and tap the i icon (information circle) next to it.

Scroll down and tap Block this Caller. The number is now blocked — that caller's calls and messages won't come through, and they'll hear a message saying your number isn't accepting calls.

You can also block a number from a text message the same way: open the message thread, tap the contact name or number at the top, then tap Block this Caller. If you change your mind, go back to Settings > Phone > Blocked Contacts and swipe left on any number to unblock it.

Use a third-party call-filtering app

Apps like Nomorobo, RoboKiller, and Truecaller filter spam calls using databases of known spam numbers. They work differently than the built-in silencing feature — they let you see who called, but block the call before it rings through.

Download one from the App Store, open it, and follow the setup steps. Most will ask permission to access your contacts and call history. Once active, the app screens incoming calls against its spam database and blocks matches automatically. You can usually see a log of blocked calls in the app itself.

These apps vary in how aggressive they are — some block more numbers than others, and some may occasionally block legitimate calls. Read the reviews for the app you're considering to see whether other users found it too strict. Many offer a free version with basic filtering and a paid version with more features.

What happens when you block a caller

A blocked caller can still leave voicemails, but they won't see a "delivered" message or know for certain they've been blocked — their call just won't go through. They'll hear a message saying your number isn't accepting calls, which could mean you're on another call, your phone is off, or you've blocked them.

The blocked caller won't appear in your recent calls list, and you won't get a notification that they tried to reach you. If they text you, the message goes to a separate folder in the Messages app called Blocked, which you can view anytime.

Why unknown callers keep getting through

Spam callers use technology called spoofing to make their number look like a local number or a business you might recognize. Because the number changes with every call, blocking one number doesn't stop the next call from a different spoofed number. That's why the "Silence Unknown Callers" feature works better than blocking individual numbers — it stops all unknown numbers at once, rather than playing catch-up.

Phone carriers like Verizon, AT&T, and T-Mobile also offer their own spam-filtering services, sometimes included free with your plan and sometimes as an add-on. Check your carrier's website or call customer service to see what's available to you.

Recovering if you blocked someone by mistake

If you blocked a number and now want to hear from them again, go to Settings > Phone > Blocked Contacts. Find the number in the list and swipe left on it, then tap Unblock. The next time they call, it will ring through normally.

If you used "Silence Unknown Callers" and blocked someone important, you can turn the feature off the same way you turned it on: Settings > Phone > Call Blocking & Identification, then toggle Silence Unknown Callers off. After that, all unknown callers will ring through again.

Frequently Asked Questions

Will the person I blocked know I blocked them?

No. They'll hear a message saying your number isn't accepting calls, which could mean several things. They won't receive a notification that you blocked them, and there's no way for them to know for certain unless you tell them.

Can I block calls but still get their voicemails?

Yes. Blocked callers can still leave voicemails — the block only stops the call from ringing through. You can listen to their voicemail in the Voicemail tab of the Phone app whenever you want.

What's the difference between blocking and silencing unknown callers?

Blocking stops a specific number you choose. Silencing unknown callers stops all calls from numbers not in your contacts, recent calls, or Siri suggestions. Blocking is for individual numbers; silencing is for all unknowns at once.

Do I need to pay for call-blocking apps?

Most offer a free version with basic filtering. Paid versions usually add features like more aggressive filtering, detailed call logs, or spam reporting. Try the free version first to see if it meets your needs.

Will blocking unknown callers stop robocalls?

It will stop them from ringing your phone, but robocalls often use spoofed numbers that change with each call. Blocking individual numbers won't stop the next call from a different spoofed number. "Silence Unknown Callers" or a third-party app works better because it filters by pattern rather than individual numbers.