iPhone has a built-in setting to block calls that hide their number
You can prevent calls from "No Caller ID" or blocked numbers from reaching your iPhone by turning on Silence Unknown Callers in the Phone app settings. This feature sends any call from a number not in your contacts, recent calls, or Mail directly to voicemail without ringing your phone. It is the most direct way to stop anonymous calls from interrupting you.
The setting works on iPhone XS, iPhone XR, and all newer models running iOS 13 or later. If you have an older iPhone, you will need to use a different method — either blocking individual numbers manually or using a third-party call-blocking app.
Key Takeaways
- Silence Unknown Callers sends blocked numbers straight to voicemail without alerting you, and works automatically once turned on.
- This setting blocks any number not already in your contacts or recent call history, so legitimate callers you have not saved will also be silenced.
- You can manually block specific numbers one at a time through the Phone app or by adding them to a contact and marking it as blocked.
- Third-party apps like Nomorobo or RoboKiller can filter calls more intelligently, distinguishing between spam and legitimate unknown numbers.
How to turn on Silence Unknown Callers
Open the Phone app on your home screen. Tap the Keypad tab at the bottom, then tap the three dots (more options) in the upper right corner. Select Settings.
Scroll down and tap Silence Unknown Callers. Toggle the switch to the right so it turns green. Once enabled, any call from a number not in your phone will go directly to voicemail. You will not see a notification or hear a ring.
If you want to check voicemails from blocked calls, open the Phone app, tap Voicemail, and listen to the messages. You can return the call from there if you recognize the number.
What happens when you block unknown callers
When Silence Unknown Callers is on, your phone will only ring for numbers you have saved in Contacts, numbers from your recent call history, and numbers that have sent you messages through iMessage or SMS. Everyone else goes to voicemail without any alert on your screen.
This means legitimate callers — a doctor's office calling about an appointment, a delivery driver, a business you called earlier — will not reach you when ready if their number is not in your contacts. They can leave a voicemail, and you can call them back. Some people turn this setting on only at night or during work hours to avoid the inconvenience during the day.
Blocking specific numbers manually
If you want to block only certain numbers rather than all unknown callers, you can block them one at a time. Open the Phone app and go to Recents. Find the number you want to block, tap the information icon (i) next to it, scroll down, and tap Block this Caller. Confirm by tapping Block Contact.
You can also block a number from a voicemail. In the Voicemail tab, swipe left on the message from the number you want to block, tap the trash icon, then tap Block this Caller. Blocked numbers will not be able to call or text you, and their calls will go straight to voicemail.
To see all your blocked numbers, go to Phone settings, scroll down to Blocked Contacts, and tap it. You can unblock any number by tapping Edit and then the minus sign next to the contact.
Using third-party call-blocking apps
Apps like Nomorobo, RoboKiller, and Truecaller use databases of known spam and scam numbers to filter calls more intelligently than Silence Unknown Callers. They can block robocalls and spam while still letting through calls from unknown legitimate numbers. These apps are available on the App Store.
After installing a call-blocking app, you need to give it permission to filter calls. Go to Settings, tap Phone, then Call Blocking & Identification. Toggle on the app you installed. The app will then intercept calls before they reach your phone and block known spam numbers automatically.
Third-party apps work alongside Silence Unknown Callers — you can use both at the same time. The app handles spam filtering, and Silence Unknown Callers handles any remaining unknown numbers.
Differences between blocking and silencing
Silencing unknown callers (the Silence Unknown Callers setting) sends calls from numbers not in your contacts to voicemail without notifying you. You will not know the call came in unless you check voicemail later.
Blocking a specific number prevents that contact from calling or texting you at all. They will hear a message that the call could not go through. Blocked numbers can still leave voicemails, but you will not receive notifications.
If you want to stop calls from No Caller ID specifically — calls where the number is intentionally hidden — Silence Unknown Callers is the only built-in option. Blocking works on numbers you can see, not on hidden ones.
Troubleshooting when blocking does not work
If you have Silence Unknown Callers on and still receive calls from unknown numbers, check that the setting is actually enabled. Go to Phone settings and confirm the toggle is green. If it is, restart your iPhone by holding the power button and swiping to power off, then turning it back on.
If you are using a third-party app and it is not blocking calls, make sure it has permission to filter calls. Go to Settings > Phone > Call Blocking & Identification and confirm the app is toggled on. Some apps require you to add numbers to a block list manually rather than filtering automatically.
No Caller ID calls that come through despite your settings may be from spoofed numbers — calls where someone has masked their real number to appear as "No Caller ID." These are harder to block because the phone cannot identify the actual source. A third-party app with spam detection may catch some, but no method blocks all spoofed calls.
Frequently Asked Questions
Will people know I blocked their number?
When you block a specific contact, they will hear a message that the call could not go through, but they will not receive a notification saying you blocked them. With Silence Unknown Callers, they will not know — their call straightforward goes to voicemail like a missed call.
Can I block No Caller ID on older iPhones?
Silence Unknown Callers requires iPhone XS or newer with iOS 13 or later. On older iPhones, you can only block individual numbers manually or use a third-party app. You cannot block all unknown callers at once with a built-in setting.
What if I need to receive calls from unknown numbers for work?
You can turn Silence Unknown Callers on and off in Phone settings whenever you need to. During work hours, turn it off so unknown callers reach you. Turn it back on at night or when you do not want interruptions. You can also use a third-party app that lets you whitelist certain numbers or types of calls.
Do blocked callers still reach my voicemail?
Yes. Both blocked numbers and silenced unknown callers can leave voicemails. You will not be notified when they do, but the messages will be in your Voicemail tab if you check it. You can listen and call them back if you choose.
Can I block calls from a specific area code?
iPhone does not have a built-in setting to block entire area codes. You would need to use a third-party app that offers this feature, or block numbers individually as they call you. Some call-blocking apps let you create rules based on area code, but this requires the app to be active and configured.