What you can do when an unknown number calls

Your phone's built-in tools can often identify who called you, and several free services can help you look up numbers after the fact. The fastest method depends on what information you have — whether you answered the call, whether you have the number, and what kind of phone you use.

If you answered and heard a voice, you may recognize the person or business immediately. If you didn't answer, or the caller didn't speak, you have several options: check your phone's call log, use a reverse phone lookup service, or search the number directly in a search engine. Some of these methods work better for business numbers than personal ones.

Key Takeaways

  • Your phone's call history shows the number, time, and duration of calls — check there first before using any other tool.
  • Reverse phone lookup services like TrueCaller, WhitePages, and Spokeo can identify business numbers and some personal numbers for free, though results vary by region.
  • Searching the number directly in Google often surfaces complaints, business listings, or forum posts if others have reported the same number.
  • Your phone's native blocking features (Do Not Disturb, call filtering) and carrier tools can stop unwanted calls without needing a third-party app.
  • If a number keeps calling after you block it, or if you suspect fraud, report it to the Federal Trade Commission at reportfraud.ftc.gov.

Check your phone's call log first

Every smartphone keeps a record of incoming calls, including the number, the date, the time, and how long the call lasted. This is your starting point — it shows you exactly what number called and when, which you'll need for any lookup service.

On an iPhone, open the Phone app and tap the Recents tab at the bottom. On Android, open the Phone app and tap the call history or recent calls icon (usually at the top). Both show a list of recent calls. Tap any number to see more details, and you can call it back, message it, or add it to your contacts from there.

If the number is already in your contacts, your phone will show the name instead of just digits. If it's not, you'll see only the number — that's when you move to a lookup service.

Use reverse phone lookup services

Reverse phone lookup means searching by phone number instead of by name. Several free services let you enter a number and see what information is publicly available about it. Results are usually better for business numbers than personal ones, and coverage varies by region and how recently the number was listed.

TrueCaller is one of the most widely used. You can search for free on their website (truecaller.com) without creating an account — just enter the number and see what comes back. WhitePages (whitepages.com) and Spokeo (spokeo.com) also offer free reverse lookups, though they may ask you to create an account or show limited results unless you pay. The free versions usually show enough to tell you whether a number belongs to a business, a known spam source, or an unknown caller.

These services pull from public records, business listings, and user reports. If a number has been reported as spam by many people, you'll often see that flagged. If it's a local business, you may see the business name and address. Personal numbers are less likely to show results unless the person has listed their number publicly.

Search the number in Google

A simple Google search of the phone number often surfaces complaints, forum posts, or business information that reverse lookup services might miss. Open Google, paste the number in quotes (for example, "555-123-4567"), and search.

If the number belongs to a business, you may find their website, social media, or Google Business listing. If it's a known spam or scam number, you'll often find Reddit threads, complaint sites, or news articles warning about it. If nothing comes up, that usually means the number is either new, private, or not widely reported online.

This method is free and requires no account, but it only works if someone else has posted about the number somewhere public. It's most useful for identifying businesses or confirming that a number is associated with known scams.

Use your phone's built-in call filtering

Both iPhone and Android have native features to filter and block calls without needing a third-party app. These work on your device and don't require you to identify the caller first — they simply stop unwanted calls from reaching you.

On iPhone, go to Settings > Phone > Silence Unknown Callers. This sends calls from numbers not in your contacts to voicemail. You can still see them in your call log, but they won't ring or notify you. On Android, the method varies by phone maker, but most have a similar feature in Settings > Apps > Phone > Call Screening or Call Filter. Google Pixel phones have a built-in Call Screen feature that can automatically decline suspected spam.

Your mobile carrier (Verizon, AT&T, T-Mobile, etc.) also offers spam filtering, often free or for a small monthly fee. Verizon Call Filter, AT&T Call Protect, and T-Mobile Scam Shield are the main carrier tools. These use databases of known spam numbers and can block calls before they reach your phone. Check your carrier's website to see what's available and whether it's already turned on.

Report spam and suspected fraud

If a number keeps calling after you block it, or if you suspect the call was a scam or fraud attempt, report it to the Federal Trade Commission at reportfraud.ftc.gov. The FTC collects reports and shares patterns with law enforcement and phone carriers.

You can also report spam to your carrier directly. Most have a way to report numbers through your phone bill or account portal. If you answered a scam call and gave out personal information, follow the FTC's guidance on what to do next — the steps depend on what information was compromised.

Do not call the number back if you suspect it's a scam. Scammers sometimes use spoofed numbers (numbers that look local or familiar) to trick you into calling back, which can result in charges or further contact.

When a lookup service won't help

Some calls come from numbers that won't show up in any lookup service. Spoofed numbers — fake numbers that scammers use to appear local or to impersonate a business — often can't be traced this way. Calls from private numbers, blocked numbers, or very new numbers may also return no results.

If you can't identify the number through any of these methods, your best option is to not answer calls from that number in the future. Add it to your blocked list, or use your phone's Do Not Disturb feature to silence calls from unknown numbers. If the caller leaves a voicemail, listen to it — legitimate callers usually identify themselves.

Frequently Asked Questions

Can I find out who called me if they blocked their number?

No. A blocked or private number intentionally hides the caller's identity, and no lookup service can reveal it. If the caller leaves a voicemail, you may hear their voice or a business name, but you won't see the actual number. If they call again, they'll appear as "Unknown" or "Private" each time.

Is it safe to use reverse phone lookup websites?

Free reverse lookup websites are generally safe to use — you're only entering a phone number, not personal information about yourself. However, some sites may ask you to create an account or offer paid services. Read the privacy policy before signing up, and avoid sites that ask for your Social Security number or financial information.

What should I do if I answered a scam call and gave out information?

The steps depend on what you shared. If you gave a credit card number, contact your bank immediately. If you shared your Social Security number, consider placing a fraud alert with the credit bureaus. Visit identitytheft.gov for a step-by-step recovery plan. Report the call to the FTC at reportfraud.ftc.gov so they can track the scam.

Will blocking a number stop them from calling back?

Blocking stops calls from that specific number from reaching you, but scammers often use different numbers each time. If the same caller keeps using new numbers, your carrier's spam filter or your phone's "Silence Unknown Callers" feature will be more effective than blocking individual numbers.

Can I trace a call to find out where it came from?

You can see the number and sometimes the general location (city or region) through reverse lookup services, but you can't trace a call to a physical address the way police can. If you suspect a crime, contact local law enforcement and provide them with the number and details of the call. They have tools and legal authority that civilians don't.