To stop spam calls in the US, do three things: register your number on the National Do Not Call Registry (free, and legitimate telemarketers must stop calling), turn on your phone's built-in call filtering, and report the calls that still get through. Be realistic about what each one does. The Registry does not block calls, and it will not stop scammers, who ignore it.
What each layer does and does not do
| Layer | Helps with | Does not stop |
|---|---|---|
| National Do Not Call Registry | Sales calls from legitimate companies | Scammers; political, charity, survey and debt collection calls; companies you recently did business with |
| Phone filtering | Calls from numbers you do not know | A legitimate call from a new number may land in voicemail; spoofed numbers that look familiar |
| Carrier tools and apps | Labeling or blocking likely scam calls | Every scam: the FTC says blocking cannot catch them all |
| Reporting | Puts the call on record with the FTC | The call you just got |
Register on the National Do Not Call Registry
The FTC's Registry FAQ gives the steps. Registration is free.
- Go to donotcall.gov, or call 1-888-382-1222 (TTY 1-866-290-4236) from the phone you want to register.
- If you register online, click the link in the confirmation email within 72 hours.
- Wait. Your number should show up on the Registry the next day, but it can take up to 31 days for sales calls to stop.
Your registration never expires, and cell phones are covered. Business and fax numbers are not. Some calls can still reach you: political, charitable, debt collection, purely informational and survey calls, as long as they contain no sales pitch, plus calls from companies you recently did business with or gave written permission to call. If you ask a company to stop, it must.
Robocalls, spoofing and STIR/SHAKEN
A recorded sales message is illegal without your written permission, and the FTC says such calls are probably a scam whether or not you are registered. Hang up. Do not press any key, because that can lead to more calls, and do not call back.
Caller ID authentication, known as STIR/SHAKEN, is the industry framework aimed at illegal spoofing. As the FCC explains, the originating carrier signs a call's caller ID as legitimate and other carriers validate that signature before the call reaches you. Even so, the FTC notes that scammers often spoof caller ID names and numbers. Treat the number on your screen as a hint, not proof: if a "bank" or "agency" calls, hang up and dial the number on your card or its official site.
Phone settings that block and filter
| Phone | Where | What it does |
|---|---|---|
| iPhone, unknown callers | Settings > Apps > Phone > Screen Unknown Callers | Never, Ask Reason for Calling, or Silence (sends the call to voicemail) |
| iPhone, filtering | Settings > Apps > Phone > Call Filtering | Turn on Unknown Callers and the spam filter; filtered calls go to separate lists |
| iPhone, block a number | Phone > Recents > tap the number > Block Caller | Blocked callers can leave voicemail but you are not notified; the list is under Settings > Privacy & Security > Blocked Contacts |
| Android, Phone by Google | Phone > More options > Settings > Caller ID & spam | "See caller ID & spam" is on by default; turn on "Filter spam calls" to silence suspected spam (filtered calls still appear in call history) |
| Android, block and report | Phone > Home > tap the call > Block or Report spam | Blocks the number and reports it; "Not spam" undoes a mistake |
These paths come from Apple and Google. Older iOS versions use different menus, the iPhone does not screen calls while roaming, and other Android brands name their filters differently, so check your device's help page.
Carrier tools and call-blocking apps
The FTC's call-blocking guide says to ask your phone company which blocking or labeling services it offers, using a phone number or website you already know is real. Some are free and some cost money. Call-blocking apps work like a filter and can block by area code, keep allow and block lists, or send suspicious calls to voicemail. Compare them by app store ratings, expert reviews or the list at ctia.org, and read the privacy policy, because some apps access your contacts.
How to report unwanted calls
Use the form at donotcall.gov. You can report a sales call that arrived after your number was on the Registry for 31 days, and you can report any robocall whether or not you are registered. Include your number, the caller ID number, any callback number, and the date and time. If you lost money, report it at ReportFraud.ftc.gov instead. For text and voice scams, see our guides on scam texts and AI voice scams.
If your business makes sales calls: staying inside the rules
The FTC's Telemarketing Sales Rule covers businesses and individuals that take part in telemarketing, and sellers can be liable for calls a telemarketer makes for them. Most calls between a telemarketer and another business are exempt, except calls selling office or cleaning supplies or pitching individual employees for personal purchases. Checklist, based on the FTC's Do Not Call Q&A for sellers:
- Subscribe: access the Registry only through telemarketing.donotcall.gov. Data for up to five area codes is free, and fees apply beyond that, so check the current schedule. A seller needs its own subscription even when a call center dials for it.
- Scrub every 31 days: synchronize your lists at least every 31 days and delete registered numbers.
- Keep your own list: honor "do not call me again" requests and keep a company-specific do-not-call list.
- Know the relationship windows: a purchase or other transaction gives you 18 months from the last payment, transaction or shipment, and an inquiry or application gives three months. A specific request to stop overrides both.
- Get written permission: it must be express, include the phone number and a signature (electronic is fine online), and the consumer can revoke it. Prerecorded calls need consent that says so and cannot be a condition of a purchase.
- Mind the clock and the caller ID: the FTC lists calling before 8 a.m. or after 9 p.m. as abusive, and you must transmit caller ID information. At the start of a sales call, say who the seller is and that the purpose is to sell.
- Document it: the safe harbor for honest mistakes requires written procedures, staff training, monitoring, your own list, registry checks within 31 days of calling with records kept, and an error behind the violation.
The FTC lists civil penalties of up to $53,088 per violation, and each call may count, with the figure adjusted over time. The FCC has separate robocall rules, so check fcc.gov before a campaign. For anything borderline, ask a lawyer: this is general information, not legal advice, and a messaging tool such as WhatsApp Business with opt-in is often safer than cold calls.
Frequently asked questions
Does the National Do Not Call Registry actually work?
It tells legitimate telemarketers which numbers not to call, and sales calls can take up to 31 days to stop. It does not block calls and it will not stop scammers, so pair it with phone filtering.
Why am I still getting spam calls after I registered?
Scammers ignore the Registry, and some callers are allowed: political, charity, survey and debt collection calls, and companies you have a relationship with or gave permission. If a seller calls after 31 days, report it at donotcall.gov.
Does my Do Not Call registration expire?
No. The FTC says your registration never expires, and it covers cell phones. It does not cover business or fax numbers.
Should I press a number to be taken off the call list?
No. For an illegal robocall, hang up, do not call back and do not press any key, since that can lead to more calls. Report it at donotcall.gov, or at ReportFraud.ftc.gov if you lost money.
Sources: FTC: National Do Not Call Registry FAQs · FTC: How To Block Unwanted Calls · FTC Consumer Advice: Five ways to help you cut down on unwanted calls (August 2025) · DoNotCall.gov: Reporting unwanted calls · FCC: Combating Spoofed Robocalls with Caller ID Authentication · FTC: Q&A for Telemarketers & Sellers About DNC Provisions in the TSR · FTC: Complying with the Telemarketing Sales Rule · Apple Support: Manage unknown callers on iPhone · Apple Support: Block phone numbers, contacts, and emails on your iPhone or iPad · Google Phone app Help: Use caller ID & spam protection
