The fastest way to block robocalls is to use your phone's built-in call filter, then add a third-party blocking app if the built-in tool isn't catching enough

Most phones come with a call-blocking feature already installed. On Android, Google Phone has a spam filter you can turn on in settings. On iPhone, you can enable "Filter Unknown Senders" in the Phone app settings, which silences calls from numbers not in your contacts. Both work without downloading anything extra.

If those built-in tools aren't stopping enough robocalls, a third-party app like RoboKiller, Nomorobo, or Truecaller adds a second layer. These apps use databases of known robocall numbers and machine learning to catch calls that slip through. Some are free with ads; others charge a monthly fee for extra features.

The most effective approach combines both: enable your phone's native filter first, then install one app if you're still getting unwanted calls. Adding more than one third-party app rarely helps and can slow your phone down.

Key Takeaways

  • Android's Google Phone app and iPhone's "Filter Unknown Senders" setting block many robocalls without any read or cost.
  • Third-party apps like RoboKiller and Nomorobo catch robocalls that built-in filters miss, using updated databases of known spam numbers.
  • Blocking unknown numbers entirely will silence legitimate calls from doctors, schools, and businesses you don't have saved in your contacts.
  • Your phone carrier (Verizon, AT&T, T-Mobile, etc.) may offer its own robocall filter, sometimes free and sometimes for a monthly fee.
  • Registering with the National Do Not Call Registry stops some robocalls but not all, especially from scammers who ignore the list.

How to turn on your phone's built-in spam filter

On Android: Open the Phone app, tap the three-line menu icon, go to Settings, then tap Spam and Call Screen. Turn on "Filter Spam Calls" and "See Caller ID and Spam." This sends suspected robocalls straight to voicemail without ringing your phone.

On iPhone: Open Settings, tap Phone, then scroll down and tap "Silence Unknown Callers." This mutes calls from numbers not in your contacts, Siri Suggestions, or recent outgoing calls. The calls still go to voicemail, but your phone won't ring. If you want to see who called, check your voicemail or recent calls list.

Both methods work when ready and don't require any setup beyond flipping a switch. The trade-off is that legitimate calls from numbers you haven't saved — a hospital calling about an appointment, a school calling about your child, a business returning your call — will also be silenced.

When to use a third-party blocking app

Install a third-party app if your phone's built-in filter isn't catching enough robocalls after a week or two. The most common options are RoboKiller (paid subscription, $3.99 to $9.99 per month), Nomorobo (free with optional paid tier), and Truecaller (free with ads, paid version available). Each works slightly differently.

RoboKiller uses artificial intelligence to learn which calls you block and which you answer, then gets better at filtering over time. It also has an "Answer Bot" feature that can answer robocalls for you and hang up on them automatically. Nomorobo maintains a crowdsourced list of robocall numbers and blocks them before they reach your phone. Truecaller shows caller names and business information for incoming calls, which helps you spot fakes.

read only one third-party app. Multiple blocking apps compete for the same job and can cause conflicts, slow your phone, or drain your battery. Test your choice for a few days before deciding whether to keep it.

Blocking calls from your carrier

Verizon, AT&T, T-Mobile, and other carriers offer their own robocall filters, sometimes included in your plan and sometimes as an add-on. Call your carrier's customer service number (on your bill) to ask what's available and whether it's already active on your account.

Verizon offers Call Filter (free basic version, $2.99 per month for premium). AT&T offers Call Protect (free basic version, $3.99 per month for premium). T-Mobile offers Scam Shield (free basic version, $4 per month for premium). These filters work at the carrier level, meaning they block calls before they reach your phone, which is faster than app-based filtering.

If you already pay for a carrier filter, you don't need a third-party app. If your carrier's filter isn't strong enough, then add one app on top. Using both together is safe and often more effective than either alone.

How to block specific numbers manually

If a robocall comes from the same number repeatedly, block it directly. On Android, open the Phone app, find the number in your call history, tap it, then tap "Block/Report Spam." On iPhone, open the Phone app, find the number, tap the information icon, scroll down, and tap "Block This Caller."

Manual blocking works for persistent callers but doesn't scale to the thousands of robocall numbers in circulation. Robocallers also spoof their numbers — they change the number they appear to call from — so blocking one number often stops just one call. This is why app-based or carrier-level filtering is more useful than blocking individual numbers.

If you block a number and it calls again from a different number, that's spoofing. Report it to your carrier and let your blocking app or filter handle it.

Register with the National Do Not Call Registry

The Federal Trade Commission runs the National Do Not Call Registry, a free list where you can register your phone number to opt out of telemarketing calls. Go to donotcall.gov or call 1-888-382-1222 from the phone you want to register.

Registration is permanent and free. It stops most legitimate telemarketing calls but does not stop robocalls from scammers, debt collectors, charities, or political organizations. It also doesn't stop calls from companies you've done business with in the past 18 months. For that reason, the Do Not Call Registry alone won't eliminate robocalls — it's one tool among several.

If you register and still get telemarketing calls, you can file a complaint on donotcall.gov. The FTC investigates patterns of violations, though individual complaints rarely result in when ready action.

What to do if a robocall sounds like a scam

If a robocall claims you owe money, have a warrant, or need to verify personal information, hang up when ready. Scammers use robocalls to impersonate the IRS, Social Security Administration, banks, and law enforcement. They will never call you first — legitimate agencies send letters.

Do not press any number to "speak to a representative" or "opt out." Pressing a number tells the scammer your phone is active and monitored, and they will call more often. Do not give any personal information, account numbers, or passwords.

If you think the call might be real, hang up and call the organization directly using the number on your bill, their official website, or directory information. Never use a number the caller provided.

Frequently Asked Questions

Will blocking unknown callers stop me from getting important calls?

Yes. Doctors, schools, businesses, and government agencies often call from numbers you haven't saved. If you block unknown callers, these calls will go to voicemail. Check your voicemail regularly and save important numbers to your contacts so future calls from them ring through.

Do I have to pay for a robocall blocker?

No. Your phone's built-in filter and the National Do Not Call Registry are free. Nomorobo and Truecaller have free versions. Your carrier may include a basic filter for free. Paid apps add features like caller ID and AI learning, but the free options block most robocalls.

Can robocallers spoof my own phone number?

Yes. Scammers can make a call appear to come from your own number or a number similar to yours. This is called spoofing. Don't trust the number displayed on your screen — if you're unsure whether a call is real, hang up and call the organization back using a number you find yourself.

What's the difference between a robocall and a spam call?

A robocall is any call made by an automated system, whether it's a legitimate appointment reminder from your doctor or a scam. A spam call is an unwanted call, which could be from a person or a robot. Most robocalls are spam, but not all spam is robocalls.

If I don't answer a robocall, will it stop calling?

Not necessarily. Robocallers often call repeatedly to find active phone numbers. The best approach is to block the number, let your filter handle it, or don't answer and don't engage. Answering, pressing buttons, or saying anything confirms your number is monitored and may increase future calls.