How do I block unknown numbers on Android?

Open the Phone app, tap ⋮ → Settings → Blocked numbers, and turn on Unknown (Google Pixel and Xiaomi). On Samsung, go to Settings → Block numbers and turn on Block calls from unknown numbers. This stops callers who hide their number; callers whose number shows but isn't in your contacts still get through.

Does Android have "Silence Unknown Callers" like iPhone?

Not as a single Phone-app switch. The closest equivalents are Do Not Disturb with the People setting limited to your contacts (calls from anyone else are silenced and go to voicemail), and, on Pixel phones in supported countries, Call Screen, which screens first-time callers before your phone rings.

Do blocked unknown callers go to voicemail?

On the Google Phone app, if visual voicemail is on, blocked callers cannot leave voicemails, and calls received while blocked don't appear in your call history. Google doesn't document what the caller hears. Samsung's support page doesn't describe the caller's experience either.

How do I block private numbers on a Samsung phone?

Open the Phone app → More options (⋮) → Settings → Block numbers, and turn on Block calls from unknown numbers. Samsung lists this under its Smart Call feature and notes it may not be available with certain carriers.

Will my carrier's spam filter block private numbers?

Carrier filters such as Verizon Call Filter and AT&T ActiveArmor block calls scored as spam or fraud, based on network data. Their published feature lists don't describe blocking hidden or private numbers, so use the Phone app's Unknown switch for those and the carrier filter for spam.

How to Block Unknown and Private Numbers on Android (2026)

NoDial Editorial ／ 2026-10-08

"Block unknown numbers" sounds like one setting, but on Android it is three different jobs. A caller who hides their number ("Private number", "No Caller ID") is stopped by one switch in the Phone app. A caller whose number shows but isn't in your contacts — what iPhone users mean by silence unknown callers — is not touched by that switch at all, and needs a different tool. And one specific number that keeps calling is a third problem again. This guide walks through each one on Pixel, Samsung, and Xiaomi phones: which setting does what, what you'll see afterwards, and what still gets through.

NoCall: Blacklist Call BlockerBlock unwanted calls before they ring.

NoDial: Block Outgoing CallsBlocks calls to numbers you choose

Steps are current as of October 2026. Menu names vary by phone maker, carrier, and Android version. Carrier features depend on your mobile operator and plan.

1. The short answer

Pick the line that matches the calls you want to stop:

The caller's number is hidden — shown as "Private number", "Unknown", "No Caller ID", or "Withheld". Open the Phone app → ⋮ → Settings → Blocked numbers → turn on Unknown (Pixel and Xiaomi), or Block numbers → Block calls from unknown numbers (Samsung). Section 3.
The number shows, but it isn't in your contacts — the Phone-app switch above does not catch these. Google's own help page says you "will still receive calls from phone numbers that are not stored in your contacts." Use Do Not Disturb with calls limited to your contacts, or Pixel's Call Screen. Section 4.
Suspected spam and robocalls — turn on Filter spam calls in the Phone app, and your carrier's free filter (Verizon Call Filter, AT&T ActiveArmor, T-Mobile Scam Shield). Section 5.
One specific number that keeps calling, or calls from abroad — block the number itself in the Phone app, or use a call-blocking app such as NoCall that refuses listed numbers and calls from other countries before they ring. Section 6.

KEY POINT

On Android, the switch called "Unknown" blocks callers who hide their number. It does not block callers who simply aren't saved in your contacts. If you want the iPhone-style "only my contacts can ring me", that's Do Not Disturb or Call Screen — not the Blocked numbers switch.

2. "Unknown" means three different things

Most of the confusion around this topic comes from one word being used for three kinds of caller:

Private, withheld, or No Caller ID — the caller deliberately hides their number (in many countries by dialling a prefix such as #31# before the number). Your phone receives no number at all. This is what Google means by "Unknown": its help page describes the switch as blocking "calls from private or unidentified numbers".
Unidentified — the network couldn't deliver a number, for example on some international routes or from some business phone systems. Your phone shows "Unknown" even though the caller didn't hide anything. Google's switch catches these too.
Not in your contacts — a perfectly ordinary number that you just haven't saved. This is what Apple means by "unknown". Apple's iPhone guide defines Silence Unknown Callers as sending "calls from unknown numbers" to voicemail while calls "from people in your contacts, recent outgoing calls, and Siri Suggestions" still ring.

So a Pixel's "Unknown" toggle and an iPhone's "Silence Unknown Callers" are not the same feature, even though they sound identical. Android's Phone app has no single switch for the Apple meaning; the closest equivalents are covered in section 4.

RULE OF THUMB

If the incoming call shows digits, the "Unknown" switch won't stop it. If it shows words — Private, Unknown, No Caller ID, Withheld — it will.

3. Method 1 — Block private and unidentified numbers (Pixel, Samsung, Xiaomi)

This is the right tool when the calls you want gone arrive with no number at all. It's a single switch, separate from blocking individual numbers, and it exists on every major Android maker's Phone app under a slightly different name.

Google Pixel, and any phone using the Google Phone app:

Open the Phone app.
Tap More (⋮) → Settings → Blocked numbers.
Turn on Unknown.

Google's help page spells out both the effect and the limit: "This will block calls from private or unidentified numbers. You will still receive calls from phone numbers that are not stored in your contacts." Two side effects worth knowing before you flip it: "Any calls you got from the number while it was blocked won't show in your call history," and "If visual voicemail is on, blocked callers cannot leave voicemails." In other words, a hidden-number caller doesn't just stop ringing — they leave no trace at all.

Samsung Galaxy:

Open the Phone app → More options (⋮) → Settings.
Tap Block numbers.
Turn on Block calls from unknown numbers.

Samsung's support page lists this under "Blocking spam, unknown, or private numbers with Smart Call" and adds that "Smart Call may not be available with certain carriers." Samsung doesn't define "unknown" on that page, and the wording of the toggle has changed between One UI versions, so if yours reads "Block unknown/private numbers" it is the same switch.

Xiaomi, Redmi, and POCO:

Open the Phone app → the three-dot icon at the upper right → Settings.
Open Blocked numbers.
Enable Unknown "to block calls from unidentified callers", as Xiaomi's own FAQ puts it.

WHAT KEEPS WORKING

Every call that shows a number — saved or not — still rings. The trade-off is in the other direction: callers who legitimately hide their number (some clinics, hospitals, and workplaces route outgoing calls with the ID withheld) are caught by the same switch and, with visual voicemail on, can't even leave a message.

4. Method 2 — Silence callers who aren't in your contacts

If what you actually want is "only people I know can make my phone ring", you've left the Blocked numbers screen behind. Android has two tools for this, and it's important to be precise about what each one does, because neither blocks the call the way Method 1 does.

Do Not Disturb, limited to your contacts. Google's Android help page describes Do Not Disturb (now part of "Modes") as a way to choose what to block or allow under "Notification filters", with a People setting to "block or allow calls, messages, or conversations" and a separate Allow repeat callers option "to let a call through if the same person calls twice in 15 minutes." The path is Settings → Modes → Do Not Disturb, then People. Under People you choose who may call through — for example only your contacts, or only starred contacts; the exact labels vary by phone, as Google's page notes ("Settings can vary by phone").

What this does: calls from anyone outside your chosen group don't ring, vibrate, or light up the screen. What it doesn't do: refuse the call. The call still arrives, shows in your call history, and goes to voicemail the way any unanswered call would. It also silences everything else Do Not Disturb silences — notifications, alarms depending on your settings — so it's a mode you switch on for a stretch of time, not a permanent filter that only affects phone calls. If you want the phone to ring normally for everyone except hidden numbers, that's Method 1, not this.

Pixel Call Screen. On Pixel phones in the US, UK, Canada, Australia, and Ireland, the Phone app can screen calls automatically before they ring. Google's help page describes protection levels — "Maximum protection", "Medium protection", "Basic protection" — and the categories it screens: "Spam", "Possibly faked numbers", and "First-time callers". A screened spam call is hung up for you; for a legitimate caller, "your phone rings and shows you how the caller responded." The path is Phone → More → Settings → Spam and Call Screen → Call Screen. This is the closest thing Android has to Apple's Silence Unknown Callers: a first-time caller is asked who they are and why they're calling before your phone makes a sound, and you decide from the transcript. It's Pixel-only and limited to those countries; on other phones, Do Not Disturb above is the fallback.

SILENCE IS NOT BLOCK

Do Not Disturb hides the ring; the call still connects to voicemail and appears in your history. Call Screen intercepts and asks; you see what the caller said. Only Method 1 (hidden numbers) and Method 4 (specific numbers) actually refuse a call before it reaches you.

5. Method 3 — Your carrier's free spam filter

None of the switches above knows whether a call is spam — they act on whether the number is shown, or whether it's in your contacts. Spam filtering is a separate layer, and two free versions of it are already on most phones.

In the Google Phone app: Settings → Caller ID and spam → turn on See caller ID & spam and Filter spam calls. Google's page explains the trade: with Filter spam calls on, "You don't get missed call or voicemail notifications, but filtered calls are in your call history, and you can check your voicemail." Suspected spam is quietly diverted rather than refused.

From your carrier (US): Google's own Android guide names the three big ones — Verizon Call Filter, AT&T ActiveArmor, and T-Mobile Scam Shield. Verizon describes Call Filter as "a free service that screens and autoblocks incoming spam calls based on risk level", with the free tier covering spam detection, a spam filter you set to "High risk only", "High and medium risk", or "All risk levels", a spam and blocked-call log, and an allow list; a personal block list and caller ID by name are in the paid Call Filter Plus. AT&T's free ActiveArmor tier offers "fraud & spam call blocking" that sends unwanted calls to voicemail. Check your own carrier's page for what's included on your plan.

What carrier filters are not for: hidden numbers and numbers not in your contacts. They score calls as likely spam using network data; a quiet private-number caller with no spam history sails through. That's why Method 1 and Method 3 are usually used together rather than one instead of the other.

6. Method 4 — One number that keeps calling, or calls from abroad

Sometimes the problem isn't a category at all. It's one number, visible, not in your contacts, calling again and again — or a wave of calls from a country you have no business with. The hidden-number switch doesn't touch either, because the number is shown.

Block that number directly. In the Google Phone app: Recents → tap the number → Block / report spam. In Samsung's: Recents → the number → Block. Full steps for both, plus texts: How to Block a Number on Android.

Use a call-blocking app for a longer list, or for whole countries. Android lets you choose one app as your call screener; that app sees each incoming call and can refuse it before the phone rings. NoCall: Blacklist Call Blocker, XTV's companion app to NoDial, does two things in that role: it blocks any number you add to its list, and it can block calls from abroad — every country other than your phone's own, with exceptions you allow. The app's own setting is explicit about the edge: "Calls from other countries will be rejected before they ring. Calls with no number are not affected." So NoCall doesn't replace Method 1; it covers the numbers Method 1 can't see because they're visible. For the background on why a single missed call from an unfamiliar country is worth refusing rather than returning, see Wangiri: the one-ring scam; for carrier-level ways to stop foreign calls, see Block Calls from Other Countries on Android.

A NOTE ON NODIAL

NoDial, XTV's other app, does not block incoming calls at all — it blocks your own outgoing calls to numbers you choose. It belongs in this article for one reason: a missed call from an unknown number is often bait to make you call back. NoDial makes sure you don't.

7. Side-by-side comparison

	Blocked numbers → Unknown	Do Not Disturb (contacts only)	Pixel Call Screen	Spam filter (app or carrier)	Block a number / NoCall
Catches	Hidden or unidentified numbers	Anyone not in your allowed group	Spam, faked numbers, first-time callers	Calls scored as likely spam	Numbers you list; calls from abroad (NoCall)
Misses	Any call that shows a number	Nothing rings; but nothing is refused	Known callers; non-Pixel phones	Hidden numbers; unknown callers with no spam history	Hidden numbers (no number to match)
Is the call refused?	Yes	No — silenced	Spam: hung up. Others: screened	Diverted to voicemail	Yes, before it rings
Call history	Not recorded	Recorded	Recorded, with transcript	Recorded	In the app's history
Voicemail	Not possible if visual voicemail is on	Yes	Depends on how the caller responds	Yes	No
Where it lives	Phone app	System settings (Modes)	Phone app (Pixel only)	Phone app / carrier	Phone app / NoCall
Undo	One toggle	One tap	Protection level	One toggle	Per number / per country

8. Which method fits your situation?

Calls show "Private number" or "Unknown" and you're done with them — Method 1. Turn on Unknown (Pixel, Xiaomi) or Block calls from unknown numbers (Samsung). Accept that a clinic calling with its number withheld will be caught too.
You want the iPhone behaviour: only contacts ring — Method 2. Do Not Disturb with People set to your contacts, plus Allow repeat callers so a genuine emergency can get through on the second try. On a Pixel in a supported country, Call Screen does it more gracefully.
Robocalls and "Scam Likely" calls — Method 3. Filter spam calls in the Phone app, plus your carrier's free filter. Leave Method 1 on as well; spam filters don't catch hidden numbers.
The same visible number, over and over — Method 4. Block it in the Phone app; if the list grows, move it to NoCall.
A flood of calls from one or more foreign countries — Method 4 with NoCall's calls-from-abroad setting, or your carrier's options in Block International Calls on Android.
You want no call to ring at all for a while — none of the above; that's a different job, covered in How to Block All Incoming Calls on Android.

9. What still gets through — and who you might lose

Before you combine every switch above, it's worth listing who you cut off along with the callers you meant to.

With Unknown / private blocking on: any caller who withholds their number. Hospitals, GP surgeries, schools, and many large employers route outgoing calls through a switchboard that shows no number. They can't leave a voicemail either if visual voicemail is on, and the call won't appear in your history, so you'll never know they tried.
With Do Not Disturb limited to contacts: the delivery driver, the tradesperson, the recruiter, the pharmacy — anyone legitimate who isn't saved. Their calls go to voicemail, so you'll find them eventually, but not in real time. Allow repeat callers softens this for anyone who tries twice.
With carrier spam filtering: occasional false positives — a legitimate business line that shares a number range with a spammer. Check the spam log every so often.
What none of them stop: a number that shows, isn't in your contacts, has no spam reputation, and is calling you for the first time from your own country. For that, there's no shortcut: block it once it has called (Method 4), or let Call Screen ask it to explain itself.

10. Turning it back off

Unknown / private blocking — Phone app → Settings → Blocked numbers (Pixel, Xiaomi) or Block numbers (Samsung) → turn the switch off. Calls received while it was on won't reappear in your history.
Do Not Disturb — swipe down and tap Do Not Disturb, or Settings → Modes → Do Not Disturb → Turn off. Your People setting is kept for next time.
Call Screen — Phone → Settings → Spam and Call Screen → Call Screen → lower the protection level or turn it off.
Filter spam calls — Phone → Settings → Caller ID and spam → switch off. Carrier filters are managed in the carrier's app or account page.
A blocked number — Phone → Settings → Blocked numbers → ✕ next to the number. In NoCall, remove the number from the list or allow the country again.

11. FAQ

How do I block unknown numbers on Android?: Open the Phone app, tap ⋮ → Settings → Blocked numbers, and turn on Unknown (Google Pixel and Xiaomi). On Samsung, go to Settings → Block numbers and turn on Block calls from unknown numbers. This stops callers who hide their number; callers whose number shows but isn't in your contacts still get through.
Does Android have "Silence Unknown Callers" like iPhone?: Not as a single Phone-app switch. The closest equivalents are Do Not Disturb with the People setting limited to your contacts (calls from anyone else are silenced and go to voicemail), and, on Pixel phones in supported countries, Call Screen, which screens first-time callers before your phone rings.
Does blocking unknown numbers also block numbers not in my contacts?: No. Google's help page states that the Unknown switch blocks "calls from private or unidentified numbers" and that "you will still receive calls from phone numbers that are not stored in your contacts." To stop unsaved numbers from ringing, use Do Not Disturb or Call Screen instead.
Do blocked unknown callers go to voicemail?: On the Google Phone app, if visual voicemail is on, blocked callers cannot leave voicemails, and calls received while blocked don't appear in your call history. Google doesn't document what the caller hears. Samsung's support page doesn't describe the caller's experience either.
How do I block private numbers on a Samsung phone?: Open the Phone app → More options (⋮) → Settings → Block numbers, and turn on Block calls from unknown numbers. Samsung lists this under its Smart Call feature and notes it may not be available with certain carriers.
Will my carrier's spam filter block private numbers?: Carrier filters such as Verizon Call Filter and AT&T ActiveArmor block calls scored as spam or fraud, based on network data. Their published feature lists don't describe blocking hidden or private numbers, so use the Phone app's Unknown switch for those and the carrier filter for spam.

12. Summary

SUMMARY

"Unknown" on Android means a hidden or unidentified number, not an unsaved one. The Blocked numbers → Unknown switch (Block calls from unknown numbers on Samsung) refuses hidden-number calls and leaves no trace of them. To stop callers who aren't in your contacts, use Do Not Disturb limited to your contacts, or Pixel's Call Screen — both silence or screen rather than refuse. Spam filters from Google and your carrier handle robocalls. A specific visible number, or calls from abroad, are a job for a blocklist: the Phone app's own, or NoCall's.

Hidden / private / No Caller ID: Phone → Settings → Blocked numbers → Unknown (Pixel, Xiaomi); Block numbers → Block calls from unknown numbers (Samsung).
Not in contacts: Settings → Modes → Do Not Disturb → People; or Pixel Call Screen. Silenced, not refused.
Spam: Phone → Settings → Caller ID and spam → Filter spam calls; plus Verizon Call Filter / AT&T ActiveArmor / T-Mobile Scam Shield.
One number or one country: block it in the Phone app, or in NoCall before it rings.
NoDial doesn't touch incoming calls; it stops you calling an unknown number back.

NoCall: Blacklist Call BlockerBlock unwanted calls before they ring.

NoDial — stop yourself calling a number backOutgoing calls only. Emergency calls never blocked.

Sources

Google Phone Help, "Block or unblock a phone number" (Blocked numbers → Unknown; blocks private or unidentified numbers, not numbers outside your contacts; call history and visual voicemail behaviour) support.google.com
Google Phone Help, "Use caller ID & spam protection" (Caller ID and spam → Filter spam calls; what you do and don't get notified about) support.google.com
Google Phone Help, "Screen your calls before you answer them" (Call Screen protection levels and categories; supported countries) support.google.com
Android Help, "Limit interruptions with Modes & Do Not Disturb on Android" (Notification filters → People; Allow repeat callers within 15 minutes; settings vary by phone) support.google.com
Samsung Support (US), "Block a phone number or contact on your Galaxy phone" (Block numbers → Block calls from unknown numbers; Smart Call availability) samsung.com
Xiaomi Support, "How to block or unblock a phone number?" (Blocked numbers → Unknown "to block calls from unidentified callers") mi.com
Apple Support, "Manage unknown callers on iPhone" and iPhone User Guide, "Screen and filter calls" (definition of Silence Unknown Callers: contacts, recent outgoing calls, and Siri Suggestions still ring) support.apple.com
Android (Google), "How to Stop and Block Unwanted Spam Calls" (carrier tools: Verizon Call Filter, AT&T ActiveArmor, T-Mobile Scam Shield) android.com
Verizon, "How to Block Spam Calls & Robocalls" and "Call Filter FAQs" (free tier features; risk levels; Call Filter Plus) verizon.com
AT&T, "ActiveArmor Mobile Security" (free tier: fraud & spam call blocking) att.com
FCC, "Stop Unwanted Robocalls and Texts" (consumer guidance on carrier blocking tools and apps) fcc.gov
NoCall app, in-app text for the calls-from-abroad setting ("Calls from other countries will be rejected before they ring. Calls with no number are not affected.") play.google.com

Phone makers and carriers change these menus over time. If a step doesn't match what you see, check the maker's or carrier's current help page.