How to Block Unknown International Calls on iPhone and Android

If you were hoping for a single switch that turns away every call from outside the US, you won't find one in Apple's or Google's help pages. What they describe is a set of smaller tools: block one number, screen or silence callers you haven't saved, and filter calls flagged as spam. Used together, they cut down the ringing while still letting you review calls from people who aren't in your contacts yet.

One more wrinkle before the settings. Plenty of "international" calls arrive with a +1 in front. Country code 1 belongs to the North American Numbering Plan, which serves 20 North American countries, so a +1 number can be in the Caribbean rather than the US. Not sure where a number is from? See what country code is calling me.

iPhone

Apple says an iPhone can block specific callers and can be set to identify, screen, filter and block unknown and spam calls. The settings sit in two places.

Screen or silence unknown callers

Go to Settings > Apps > Phone. You get three choices for calls from numbers you haven't saved: Never, Ask Reason for Calling, and Silence.

• Never leaves things as they are. Unsaved numbers ring normally.
• Ask Reason for Calling is Call Screening. Your iPhone answers the unknown call, the caller gives a name and a reason, and only then does the phone ring and show you what they said.
• Silence is the blunt option. Calls from unsaved numbers don't ring, go to voicemail and still appear in Recents.

If you have relatives, a landlord or a doctor's office overseas, Ask Reason for Calling is the gentler pick. A real person gets the chance to say who they are before you decide.

Filter spam and unknown callers

In the same Phone settings, turn on the Spam filter. Calls your carrier identifies as potential spam or fraud are silenced, sent to voicemail and moved to a Spam list. The Unknown Callers filter moves calls from unknown numbers out of Recents and into their own list. Glance at both lists now and then, because a call you wanted can land there.

Block one number

Open Phone, tap Recents, tap the number (or the Info button in Classic view), scroll down and tap Block Caller. In iOS 26 you can also add a number by hand under Settings > Privacy & Security > Blocked Contacts.

A blocked number can still leave a voicemail, but you won't be notified, and the caller isn't told they were blocked.

Android (Phone by Google)

The steps below come from Google's help pages for the Phone by Google app. If your Android phone uses a different dialer, the menu names may not match.

Block and report a number

Open Phone, tap More, then Call history. Tap the call and choose Block / report spam. From then on, that number's calls are declined automatically. When the screen shows "Suspected spam caller" or "Spam," Google says the call might be spam and you can block and report it.

Turn on the spam filter

Caller ID and spam protection is on by default. Go further by turning on Filter spam calls: you stop getting missed-call and voicemail notifications for spam, while the calls stay in your history and your voicemail is still there to check. One privacy note: when someone outside your contacts calls, the feature may send that number to Google to identify a business or flag spam.

Use Call Screen

Automatic Call Screen works on Pixel phones in Australia, Canada, Ireland, the UK and the US. Manual screening is also available in the US and Canada on selected Android devices. Call Screen skips numbers saved in your contacts, and Google says it can't catch every spam call or robocall. It also won't screen calls automatically while you're roaming.

What "Unknown" really blocks

This is the setting people misread. Under Settings > Blocked numbers, turning on Unknown blocks private or unidentified numbers only. Calls from ordinary numbers that just aren't in your contacts still get through. So it won't stop a visible international number. Spam filtering, Call Screen and single-number blocks handle those.

Save the numbers you need before you filter

Several of these tools lean on your contact list. Call Screen leaves saved contacts alone, and the iPhone's Silence option only affects unsaved numbers. So before you tighten anything, add the overseas people and businesses you expect to hear from. Our guide on how to save international numbers in your contacts covers the format that lets the phone match an incoming call, and our explainer on how international numbers are written shows where the country code goes.

Carrier tools and blocking apps

Your carrier is the other layer. The FTC suggests checking your provider's website or calling customer service to see which call-blocking or call-labeling services it offers; some are free and some charge a fee. In a 2020 report, the FCC found that most voice providers offered blocking and labeling on an opt-in or opt-out basis, usually through a third-party analytics partner.

Labeling doesn't stop the call. It rings through with a tag such as "spam" or "scam likely," and you decide. Call-blocking apps go further, and the FTC notes some can block calls by geographic location or area code. That goes broader than blocking one number at a time, and the FTC flags the downside: call-blocking services might block some calls you want. A student abroad calling from a new number could be one of them.

Don't call back, and report the call

Blocking works on numbers, and caller ID can be faked: the FTC says scammers can make any name or number appear on your screen. Google itself says Call Screen can't catch every spam call, so expect the occasional one to slip through.

If a missed call looks like a one-ring scam, don't return it. The FTC warns that one-ring scam calls use area codes that look like they're in the US but belong to international numbers, often in the Caribbean. Its advice is to not pick up and not call back; the danger is the bill from calling back. Jamaica, the Bahamas and the Dominican Republic all sit inside the same +1 plan as the US. Our guide to one-ring scam calls from Caribbean area codes lists the others.

If you pick up a robocall, hang up, don't call back and don't press any key, then report it. Use DoNotCall.gov if you didn't lose money, and ReportFraud.ftc.gov if you did or you know something about the scammer. Include your number, the caller ID number even if you think it was spoofed, any callback number, and the date and time. Each business day, the FTC releases the reported numbers to help carriers and other partners working on blocking and labeling, so a report can help improve those filters.

FAQ

Can I block all international calls on my iPhone?

Not with one setting. Apple's options are blocking individual callers and screening, silencing or filtering unknown and spam calls.

Does a blocked caller know they're blocked?

On iPhone, no. They can still leave a voicemail, and you won't get a notification for it.

Why do I still get calls after turning on "Unknown" on Android?

Because that setting only covers private or unidentified numbers. Use spam filtering or Call Screen for the rest.

Sources

1. Apple Support: Screen and block calls on iPhone (iPhone User Guide) (accessed 2026-09-24)
2. Google Phone app Help: Block or unblock a phone number (accessed 2026-09-24)
3. Google Phone app Help: Use caller ID & spam protection (accessed 2026-09-24)
4. North American Numbering Plan Administrator (NANPA): About NANPA and the North American Numbering Plan (accessed 2026-09-24)
5. Apple Support: Block phone numbers, contacts, and emails on your iPhone or iPad (accessed 2026-09-24)
6. Google Phone app Help: Screen your calls before you answer them (accessed 2026-09-24)
7. Federal Trade Commission (Consumer Advice): How To Block Unwanted Calls (accessed 2026-09-24)
8. Federal Communications Commission (FCC): Call Blocking Tools Now Substantially Available to Consumers: Report on Call Blocking (June 2020) (accessed 2026-09-24)
9. Federal Trade Commission (Consumer Advice): Phone Scams (accessed 2026-09-24)
10. Federal Trade Commission (Consumer Advice): "One-ring" cell phone scam can ding your wallet (accessed 2026-09-24)
11. Federal Trade Commission (Consumer Advice): National Do Not Call Registry FAQs (accessed 2026-09-24)