Use more than one filter. For a U.S. number, register with the National Do Not Call Registry, turn on your carrier's and phone's spam controls, and let unfamiliar calls go to voicemail. Caller ID can be spoofed, and no setting blocks every unwanted call.

These steps are for U.S. consumers. The Registry mainly limits lawful telemarketing. It does not stop every scam, spoofed number, political call, charitable solicitation, or survey.

Set up the basic protections

1. Register each number at DoNotCall.gov. Open the confirmation email for each number and click its link.
2. Turn on your carrier's call protection. Start with labels if you regularly need calls from unknown numbers.
3. Use your phone's call controls. Block repeat offenders and silence or screen other unknown callers.
4. Don't engage with suspicious calls. Hang up instead of pressing a key, confirming personal details, or calling the displayed number.
5. Report scams and unwanted calls or texts. Save the date, displayed number, claimed identity, and any voicemail or message first.

Free carrier and device features are a sensible starting point. Check their blocked and spam folders so a doctor's office, school, delivery driver, or other legitimate caller doesn't disappear unnoticed.

Register for the National Do Not Call Registry

The Registry can reduce sales calls from legitimate telemarketers, but it isn't a call-blocking service.

The FTC's National Do Not Call Registry FAQs explain how to:

• Register up to three phone numbers at a time online.
• Open each confirmation email and click its link within 72 hours.
• Allow up to 31 days for telemarketers to update their lists.
• Repeat the online process if you have more than three numbers.
• Use the official site instead of paying another service to register you.

Registration stays with the number while it remains active. If a number is disconnected and later assigned to someone else, the new user should register it again.

Calls the Registry does not cover

The Registry won't stop scammers who ignore the law or falsify caller ID. It also doesn't cover every kind of call. Political calls, charitable solicitations, surveys, and some calls from companies with an existing relationship can follow different rules.

The FTC says a company may be able to call for up to 18 months after you last did business with it. If you want a particular company to stop, clearly ask it to put your number on its internal do-not-call list. Record the company's name, the date of your request, and the number that called.

Turn on carrier and phone controls

Depending on the provider, carrier tools may include caller ID, scam labels, network-level blocking, voicemail filtering, and a way to report spam. Names and prices vary. Open your carrier's official app or account page rather than using a link in an unexpected text message.

A cautious order for choosing settings is:

1. Use labels first. A warning such as "Spam Likely" gives you the choice to answer.
2. Add automatic blocking for high-confidence spam. This is more convenient, but a legitimate call can still be sent to voicemail.
3. Check the blocked and spam folders. Do this regularly when you're expecting an important call.
4. Save important callers as contacts. This makes them easier for your phone and carrier to recognize.
5. Block individual numbers after repeated calls. Blocking one number won't stop a campaign that keeps changing numbers.

On an iPhone, Apple supports screening unknown callers, silencing them, filtering spam, and reviewing calls identified as spam or fraud. See Apple's guidance on managing unknown callers. On an Android phone, open the Phone app's settings and look for options such as Caller ID and spam, Filter spam calls, or Call Screen. The wording depends on the phone, software version, and carrier.

Landline and VoIP customers should check their provider's features and their phone hardware. A mobile app may not protect a landline, and a setting available on one VoIP service may not be available on another.

Use Do Not Disturb without losing important calls

Do Not Disturb, Focus, and similar settings control interruptions. They can silence calls during certain hours or allow calls from contacts, favorites, or repeat callers. They don't remove your number from telemarketing lists, and they usually don't prevent an unknown caller from leaving a voicemail.

Consider this setup:

• Allow saved contacts and emergency contacts if your phone supports those choices.
• Send other calls to voicemail instead of rejecting every unknown number.
• Enable a repeat-caller exception only if you want that convenience.
• Check voicemail and missed-call notifications at a time that works for you.
• Keep a separate work or family contact list if important callers may use unfamiliar numbers.

A quiet-hours setting isn't the same as a legal call block. U.S. federal telemarketing rules generally restrict calls to a home before 8 a.m. or after 9 p.m. local time. That restriction doesn't stop illegal callers, and a call made during permitted hours isn't automatically safe. The California Attorney General's unwanted-call guidance summarizes those federal time limits.

Handle suspicious calls safely

A local-looking number can be spoofed. A caller who has part of your name, uses a professional voice, or offers an automated menu still hasn't proved who they are.

If you answer an unexpected call:

• Don't press a number to "speak to an agent" or remove yourself from a list.
• Don't confirm your name, address, account number, password, or one-time security code.
• Don't provide banking, card, Social Security, or Medicare information.
• Hang up if the caller creates urgency, threatens consequences, or demands payment.
• Check the request through a number or website you already trust, such as the number on a bank card or billing statement.
• If someone claims to be a family member, call that person back using a saved number.

With a suspicious text, don't click its links or reply. You can forward unwanted texts to 7726, which spells "SPAM," when your carrier supports the service. This route is for messages, not live phone calls.

Is a third-party call-blocking app worth it?

It can be useful when your carrier's tools aren't catching enough calls. A third-party app may offer a larger community-reported database, extra caller identification, call screening, or more control over unknown numbers. "AI-powered" doesn't mean it will block every scam or avoid false positives.

Before installing one, check:

• Whether blocking is free or requires a recurring subscription.
• Whether a trial renews automatically.
• What access the app requests to contacts, call history, or other phone data.
• Whether you can turn off data sharing or delete your account.
• What happens when it labels a legitimate number incorrectly.
• Whether it works with your carrier, phone type, landline, or VoIP service.
• Whether it screens a call before the phone rings or labels it afterward.

A carrier filter paired with your phone's own controls is often enough to start. Add a third-party service only after checking its permissions and billing terms. Be wary of any promise to block a guaranteed percentage of calls.

What STIR/SHAKEN can and cannot do

STIR/SHAKEN is a carrier-side framework for authenticating caller-ID information. On supported calls, the receiving provider can use it to determine whether the originating provider verified or attested to the displayed number.

That doesn't make the call safe. STIR/SHAKEN isn't a consumer setting, a fraud guarantee, or a certification that the caller is honest. It doesn't explain why someone is calling, and not every call path receives the same level of verification.

Treat an authentication result or familiar-looking label as one clue, not proof of identity. Don't disclose information just because a number appears local, familiar, or authenticated.

Report unwanted calls and keep evidence

A report may not stop the next call, but it gives regulators information about calling patterns and repeat offenders. The FTC says it analyzes reports and trends to help identify illegal callers.

Use the reporting route that fits the problem:

• Unwanted sales calls or a Do Not Call violation: Report it through DoNotCall.gov.
• A scam, impersonation attempt, or financial loss: File a report at ReportFraud.ftc.gov.
• Caller-ID spoofing, unwanted calls or texts, or a provider issue: Use the FCC Consumer Inquiries and Complaints Center.
• Spam texts: Forward the message to 7726 when supported by your carrier, then use the carrier's report-spam option.

Before deleting anything, record:

• The date and approximate time, including your time zone if relevant.
• The number shown on caller ID and any callback number the caller gave you.
• The business or agency the caller claimed to represent.
• What the caller requested and whether they left a recording or voicemail.
• Whether you had registered the number or previously told that company not to call.
• Screenshots of related texts, websites, payment requests, or caller-ID labels.

Don't call a suspicious number back just to gather more details. If you shared a password, one-time code, bank information, or card details, contact the affected institution through an official number, change any compromised passwords, and monitor the account.

If a legitimate call gets blocked

Spam filters make mistakes. A medical office may call from an unsaved number, and a small business may use several outbound numbers.

If unknown callers matter to you:

• Choose screening or labeling instead of silencing every unknown number.
• Keep your contacts current.
• Check voicemail and the phone's spam folder.
• Ask important organizations which number they use for callbacks.
• Ask your carrier to review a legitimate number that is repeatedly mislabeled.
• If your own number is being spoofed or labeled as spam, document the problem through the FCC complaint center.

Blocking one number rarely ends a spoofing campaign. Pair individual blocking with carrier filtering, voicemail screening, and nonresponse.

Common questions

Will the Do Not Call Registry stop robocalls?

No. It mainly limits calls from legitimate telemarketers that are subject to the Registry. Scammers, spoofed numbers, and some exempt callers can still get through.

Why do spam calls continue after I register?

Telemarketers may have up to 31 days to update their lists, and registration doesn't stop illegal callers. Scammers can rotate numbers or disguise caller ID. Keep your carrier and phone filters on, and report repeat calls.

Is a "Spam Likely" label always accurate?

No. Labels are predictions based on network signals, reports, and calling patterns. Let important unknown calls go to voicemail, then check the spam folder if a legitimate call may have been filtered.

What's the best first step?

Register at DoNotCall.gov, activate your carrier's protection, and turn on your phone's screening or spam filter. If a suspicious call or text arrives, don't interact with it; save the voicemail or message and record its details before reporting it.