A hand tapping a smartphone screen, the first step to taking control of unwanted calls.
Spam calls waste time, interrupt work, and sometimes hide scams that try to steal personal information or money from unsuspecting phone users every day.
The good news is that both Android and iPhone already include powerful built-in tools that can silence, filter, and block most unwanted calls automatically.
This step-by-step guide shows exactly where to find those settings, how to block a single persistent number, and when to use stronger options instead.
You do not need to buy an app to start, although carrier tools and trusted third-party apps can add another layer of protection later if needed.
What You Will Learn
Android spam filters. Learn how to turn on caller ID and spam protection in the Phone app so suspected spam calls are labeled or silenced.
iPhone call screening. Discover how Screen Unknown Callers can silence or screen unknown numbers, and how the carrier spam filter helps too.
Blocking single numbers. Find out how to block and report one repeat caller on Android and iPhone in just a few taps.
Carrier spam tools. See which free tools major United States carriers offer, and how they work alongside your phone's built-in settings.
Staying safe afterward. Get practical tips for avoiding callback scams, protecting your number, and checking voicemail without missing important calls.
Block Spam Calls on Android
Android phones do not all look identical, because Samsung, Google Pixel, and other makers use slightly different Phone apps and menu names.
The core ideas are the same, however, so use the closest matching menu on your phone if a label below looks slightly different from yours.
Start with the built-in spam filter, because it stops many unwanted calls without blocking every unknown number or silencing legitimate callers.
Turn On Caller ID and Spam Protection
Open the Phone app. Tap the three-dot menu in the top-right corner, then choose Settings to open the calling options for your device.
Tap Caller ID and spam. On Samsung phones, look instead for Caller ID and spam protection, which offers the same kind of caller identification and filtering.
Turn on See caller and spam ID. This switch lets your phone warn you about suspected spam callers and identify businesses before you decide whether to answer.
Turn on Filter spam calls where available. Suspected spam calls are then filtered automatically instead of ringing, although some Pixel phones handle this through Call Screen instead.
On newer Pixel phones, spam filtering runs through Call Screen, which can answer unknown calls automatically and show you a live transcript before you pick up.
If you cannot find Filter spam calls, check that your Phone app is updated, because menu names and features vary by device, region, and app version.
Block a Specific Number on Android
Open Recents in the Phone app. Find the unwanted call in your recent call history, then tap it or press and hold it to reveal more options.
Choose Block or Block and report spam. Reporting the number helps Google improve its spam database, which can protect other Android users from the same caller.
Confirm the block. The number can no longer reach you normally, and future calls from it will be blocked instead of ringing your phone.
Block All Unknown Numbers on Android
Blocking every unknown number is the strongest Android option, but it also silences legitimate first-time callers such as clinics, schools, and delivery drivers.
Open Phone Settings, then Blocked numbers. On Samsung phones, this menu is called Block numbers instead, but it contains the same unknown-number switch.
Turn on Unknown or Block calls from unknown numbers. Calls without a visible caller ID will then be blocked, while calls from your saved contacts continue to ring normally.
Check your blocked list and voicemail regularly if you use this option, so you do not miss an important call from a new number.
Block Spam Calls on iPhone
On iPhone, the strongest controls live in Settings under Apps and Phone, where Apple groups call screening, call filtering, and blocking in one place.
Older iPhones may show a single Silence Unknown Callers switch instead of the newer three-option screen, but the result is broadly the same.
Screen or Silence Unknown Callers
Open Settings, then tap Apps and Phone. Scroll down to Screen Unknown Callers, where you will see three choices for handling calls from unsaved numbers.
Choose Ask Reason for Calling for a middle ground. Your iPhone answers unknown calls quietly, asks the caller to state their name and reason, and only rings you afterward.
Choose Silence for maximum quiet. Calls from numbers you have not saved go straight to voicemail without ringing, although they still appear in your recent calls.
Contacts, numbers you recently called, and Siri suggestions still ring normally, so this feature targets strangers rather than people you already know.
Filter Unknown and Spam Calls
Call Filtering adds a second layer by moving unknown and carrier-flagged spam calls into separate lists, keeping your main Recents list much cleaner.
In Settings, Apps, and Phone, open Call Filtering. Turn on Unknown Callers to move those calls into their own list, away from your main call history.
Turn on the Spam filter in the same menu. Calls your carrier identifies as potential spam or fraud are silenced and moved to a dedicated Spam list.
To review filtered calls, open the Phone app, tap the filter control in Recents or Calls, then choose Unknown Callers or Spam as needed.
If a filtered number turns out to be legitimate, tap Mark as Known next to that call so future calls from it are treated normally.
Block a Specific Number on iPhone
Open the Phone app and tap Recents. Tap the small information icon beside the unwanted number to open its full call details screen.
Scroll down and tap Block this Caller. Confirm the choice, and the number will no longer be able to call you, send messages, or reach you by FaceTime.
To unblock someone later, go to Settings, Apps, Phone, and Blocked Contacts, then tap Edit and remove the number from your list.
Use Your Carrier's Free Spam Tools
Carriers add network-level protection that works before a call reaches your phone, and many of their basic spam tools are free to use.
AT&T Call Protect and ActiveArmor. These tools flag suspected spam, block fraud calls, and let you manage unwanted numbers from the app.
T-Mobile Scam Shield. This free service identifies likely scam calls, blocks scam numbers at the network level, and offers extra caller ID options.
Verizon Call Filter. The free version detects and filters spam calls, while the paid version adds caller ID details for unknown numbers.
Enable your carrier tool alongside your phone settings rather than instead of them, because layered protection catches more unwanted calls overall.
Exact features and prices vary by carrier and plan, so check your carrier app or website for the current options in your country.
Extra Tips That Actually Reduce Spam Calls
Never call back an unknown number that rang once and hung up, because one-ring scams profit when curious victims return expensive international calls.
Do not share verification codes, passwords, or bank details with any caller, even if the caller ID looks like your bank or a government agency.
Register your number with the United States Do Not Call Registry at donotcall.gov, which reduces legal telemarketing even though scammers may ignore it.
Report persistent scam calls to your carrier and, in the United States, to the Federal Trade Commission, so the numbers can be investigated and blocked.
Keep your phone software and Phone app updated, because spam detection, call screening, and scam warnings improve with newer system releases.
Use a second number or a virtual number for online sign-ups and classified ads, so your main number stays out of marketing and data-broker lists.
Frequently Asked Questions
Will blocking a number stop all spam calls?
No, blocking one number only stops that exact number, and spammers often switch numbers, spoof caller ID, or call from many different lines.
That is why filters, carrier tools, and screening matter more than manual blocking alone, because they catch patterns rather than single numbers.
Will silencing unknown callers block important calls?
It can silence legitimate first-time callers, including clinics, delivery drivers, and schools, because their numbers are not saved in your contacts.
Use Ask Reason for Calling instead if you expect such calls, and check voicemail and filtered lists regularly so nothing important is missed.
Do I need a paid spam-blocking app?
Most people do not, because built-in filters and free carrier tools already handle the majority of spam calls well enough for daily use.
A paid app may help only if you still receive heavy spam after enabling every free option, or if you want extra features like detailed caller identification.
What should I do if I answered a scam call?
Hang up immediately, do not press any key or follow instructions, and never send money, gift cards, or personal information to the caller.
Block and report the number afterward, then watch your accounts closely and contact your bank quickly if you shared any sensitive details.
Why do spam calls still appear after I enabled filtering?
Spammers constantly rotate numbers and spoof trusted caller IDs, so no single filter can recognize every new number the moment it first appears.
Keep filters and carrier tools switched on, report new spam numbers when possible, and let the databases learn from those reports over time.
Start with the free settings on your own phone today, because ten quiet minutes of setup can save hours of interruptions over the coming months.
If spam still slips through, add your carrier tool, tighten unknown-caller screening for a while, and review blocked calls before loosening anything again.