Block unknown callers directly in your phone settings

Most phones have a built-in setting to silence or block calls from numbers not in your contacts. On an iPhone, go to Settings > Phone > Silence Unknown Callers, which sends unknown calls straight to voicemail without ringing. On Android, the process varies by manufacturer — Samsung phones have Settings > Apps > Phone > Spam Protection > Block Unknown, while Google Pixel phones use Settings > Apps & Notifications > Notifications > Advanced > Spam and abuse.

These settings work when ready once turned on. Unknown callers will still be able to leave voicemail, so you can listen later if you want to know who called. The downside is that legitimate calls — from your doctor's office, a delivery driver, or a business you contacted — will also go silent, so you may miss important messages.

If you want to see who called but prevent them from ringing through, most phones let you send unknown numbers directly to voicemail instead of blocking them completely. This gives you the option to listen and call back if the message sounds important.

Key Takeaways

  • Your phone's built-in settings can silence or block unknown callers without downloading anything extra.
  • Blocking unknown callers means you will miss calls from legitimate businesses and services that are not in your contacts.
  • Most phone carriers offer free spam-blocking tools through their own apps or websites.
  • Third-party apps like TrueCaller and RoboKiller can identify callers before they ring, but require you to grant access to your contacts and call history.
  • Reporting spam numbers to your carrier helps protect other customers on the same network.

Use your phone carrier's spam-blocking service

AT&T, Verizon, T-Mobile, and most other carriers offer free spam-blocking tools built into their networks. AT&T Call Protect and Verizon Call Filter screen calls before they reach your phone and let you see which ones were flagged as spam. T-Mobile Scam Shield works the same way. These services are usually turned on by default, though you can adjust how aggressively they block calls through your carrier's app or website.

Carrier-level blocking happens before the call reaches your phone, so spam calls do not ring through at all — they are blocked at the network level. This is more effective than phone-based blocking because it catches spam before it gets to your device. You can usually see a log of blocked calls in your carrier's app if you want to check what was filtered.

Some carriers offer a premium version with extra features. AT&T Call Protect Plus and Verizon Call Filter Plus add things like caller name lookup and the ability to create custom block lists, but the free versions handle most spam without extra cost.

Try a third-party spam-blocking app

Apps like TrueCaller, RoboKiller, and Nomorobo identify incoming calls in real time and show you the caller's name or whether the number is flagged as spam before you answer. TrueCaller has a database of millions of phone numbers and can identify businesses, scammers, and spam callers. RoboKiller uses artificial intelligence to learn which calls are spam based on your behavior and can even answer robocalls with a fake voicemail to discourage repeat calls.

These apps require permission to access your contacts, call history, and sometimes your location to work properly. Read the privacy policy before installing — some apps sell anonymized data to third parties, while others keep your information private. Free versions of most apps block calls and show caller information, while paid versions add features like custom block lists and call recording.

Third-party apps work best alongside your phone's built-in settings or your carrier's service, not instead of them. If you use TrueCaller on top of your carrier's spam filter, you get two layers of protection, though this can sometimes block legitimate calls if both systems flag the same number.

Report spam numbers to stop them from calling others

When you receive a spam call, reporting it to your carrier or to the Federal Trade Commission helps prevent the same number from harassing other people. Most phones have a "Report as Spam" option in your call history — tap the number, select the option, and your carrier logs it. You can also report spam calls directly to your carrier's app or website.

The FTC maintains a national Do Not Call Registry, but it only applies to telemarketers making sales calls, not to scammers or robocalls. You can add your number to the registry at donotcall.gov, though this does not stop illegal callers. Reporting numbers to the FTC at reportfraud.ftc.gov creates a record that law enforcement can use to investigate patterns of fraud.

Carriers use reports from customers to update their spam databases, so reporting genuinely helps. If hundreds of people report the same number, your carrier is more likely to block it for everyone on the network.

Do not answer or engage with unknown callers

The safest approach to unknown callers is to let them go to voicemail. Scammers use automated systems to test whether a number is active — if you answer, they know your number works and will call again or sell it to other scammers. If you do not answer, many robocalls move on to the next number.

If you answer and realize it is a scammer, hang up when ready. Do not press any buttons, do not say anything, and do not ask to be removed from the list — these actions confirm your number is active and monitored. Scammers often use fake caller IDs that look like real businesses or government agencies, so a familiar-looking number does not mean the call is legitimate.

If a caller claims to be from your bank, the IRS, or another official agency, hang up and call the organization directly using the number on your statement or their official website. Real agencies do not call you first demanding information or payment.

Whitelist important numbers so they always ring through

If you block unknown callers at the phone level, you can create a whitelist of numbers that should always ring through even if they are not in your contacts. On iPhone, add numbers to your Favorites or create a contact for businesses you expect to call you back. On Android, add numbers to your contacts or mark them as important in your Phone app settings.

This is especially useful if you are waiting for calls from your doctor, a job interviewer, or a delivery service. Add their number to your contacts before they call, or ask them for their direct line so you can add it in advance. Some apps like RoboKiller let you create a whitelist of numbers that bypass all filtering.

Keep your whitelist small and update it regularly — the longer the list, the more spam gets through. Remove numbers once you no longer expect calls from them.

Frequently Asked Questions

Will blocking unknown callers stop legitimate businesses from reaching me?

Yes. Doctors' offices, delivery services, and customer support lines often call from numbers not in your contacts. If you block all unknown callers, you will miss these calls. Instead, ask businesses for their direct number before they call, add it to your contacts, or use your carrier's spam filter instead of blocking all unknowns.

Can I block a specific number instead of all unknown callers?

Yes. On iPhone, open the call history, tap the number, and select Block This Caller. On Android, open Phone, find the number in your call history, tap it, and select Block Number. The caller can still leave voicemail, but their calls will not ring through. You can unblock numbers anytime in your phone's settings.

Do spam-blocking apps cost money?

Most offer free versions that block calls and show caller information. Paid versions add features like call recording, custom block lists, or advanced filtering. Your carrier's spam filter is always free. You do not need to pay for basic spam protection.

What should I do if a scammer is using my own phone number to call people?

Report it to your carrier and to the FTC at reportfraud.ftc.gov. Scammers often spoof phone numbers — they make calls appear to come from your number without actually using your phone. You cannot stop this directly, but reporting it creates a record and alerts your carrier to monitor for fraud on your account.

Can I get my number removed from spam call lists?

Not directly. Spam lists are bought and sold between scammers, so asking to be removed often confirms your number is active and monitored. The best approach is to not answer unknown calls, report spam numbers to your carrier, and use your phone's built-in blocking or your carrier's spam filter.