How to block spam calls on iPhone and Android

Let unknown numbers go to screening or voicemail, and never press a key or call back to find out who it was.

Hands holding a smartphone showing an incoming call. — Photo: cottonbro studio / Pexels

Area: InformationFrom age 13Time to learn: 10 minutes

Turn on your phone's built-in spam filter and unknown-caller screening, block numbers that keep calling, and register with the Do Not Call list. The list stops sales calls from legitimate telemarketers. It does not stop scammers.

Why it matters

The FTC's advice on an illegal robocall is to hang up and not call back, and not to press a number, which could lead to more robocalls. The filters already on iPhone and Android phones can silence unknown and suspected spam numbers before they ring. The national Do Not Call lists in the US and Canada cut legal sales calls, so the calls that still get through are easier to recognize as likely scams. In fiscal year 2025, the US registry held over 258 million active registrations, and the FTC still received over 2.6 million Do Not Call complaints.

How to do it

iPhone: go to Settings > Apps > Phone > Screen Unknown Callers. Choose Ask Reason for Calling, which makes callers from numbers not in your contacts say why they are calling before your phone rings. Or choose Silence, which silences those calls and sends them to voicemail.
iPhone: on the same screen, under Call Filtering, turn on Unknown Callers and the spam filter. To check what was filtered, tap the Filter button in the Phone app and open Unknown Callers or Spam.
iPhone, to block one number: open Phone, tap Recents and tap the number (in Classic view, tap the Info button), then scroll down and tap Block Caller. A blocked caller can still leave a voicemail, but you will not be notified.
Android with the Google Phone app: tap More options > Settings > Caller ID and spam, and turn on See caller ID & spam and Filter spam calls. On Pixel phones with automatic Call Screen there is no Filter spam calls switch. Set up spam blocking under More > Settings > Spam and Call Screen (or Call Screen) instead.
Android, to block one number: open Call history, tap the call, and choose Block / report spam. To block calls from private or hidden numbers, go to More > Settings > Blocked numbers and turn on Unknown. This does not block numbers that are simply missing from your contacts.
Samsung Galaxy: in the Samsung Phone app, tap More options (three dots) > Settings. Turn on Caller ID and spam protection to filter spam. Under Block numbers, you can block a number or turn on Block calls from unknown numbers, which blocks numbers that are not in your contacts or identified by Smart Call.
US: register each number for free at DoNotCall.gov, or call 1-888-382-1222 from the phone you want to register. Registration never expires, and sales calls can take up to 31 days to stop.
Canada: register for free at LNNTE-DNCL.gc.ca or call 1-866-580-3625. Telemarketers have 31 days from the date you register to stop calling. Some callers are exempt and can still call: registered charities, political parties and candidates, surveys, and newspapers selling subscriptions. So can companies you have bought from in the past 18 months, asked about a product in the past 6 months, or given permission to call.
Add the people you need to hear from, such as your doctor, your child's school and your pharmacy, to your contacts so that screening does not silence them.
Report calls that get through. In the US, use the reporting form at DoNotCall.gov, or ReportFraud.ftc.gov if you lost money. In Canada, file a complaint with the National Do Not Call List, or report to the Canadian Anti-Fraud Centre if you lost money.

Common mistakes

Expecting the Do Not Call list to stop scam calls. It stops sales calls from companies that follow the law; scammers ignore it.
Pressing a number 'to be removed from the list', or calling back an unknown number to see who it was.
Silencing or blocking unknown callers without first adding the people you need to hear from to your contacts.
Installing a call-blocking app without reading its privacy policy, since some apps read your contacts.

You can do this when …unknown and suspected spam calls go to screening or voicemail without ringing, your number shows as registered on the Do Not Call list, and you can block a number from your recent calls without looking up how.