11 November 2026
The Flggd team
Learn what an unknown caller label really means and get step by step methods to find out who called you using *69, *57, reverse lookup, and more.
These steps are for the US and Canada unless marked otherwise. An "Unknown Caller" label usually means the network lost the caller's ID data in transit, not that someone hid it on purpose. To find out who called, check your call log, try *69 from a landline, use *57 for harassing calls, or use your carrier's spam tools. The right method depends on which label you saw and what kind of phone you use.
"Unknown Caller" and "No Caller ID" look similar on your screen, but they come from two different problems. Knowing which one you have tells you which fix can work.
"No Caller ID" means the caller chose to hide their number before placing the call. The network got the number. It just did not pass it to you.
"Unknown Caller" means the network failed to deliver the caller ID data. This happens most with international calls, older internet-based phone systems, and calls that cross incompatible networks. The number may not have been hidden at all. The data got lost on the way.
That difference matters. If the data never arrived, no tool can rebuild it. The number is simply missing from the call record.
One more thing to know: a name on your screen is not proof of who is calling. Caller ID is a data field that scammers can fake. This is called spoofing, where a caller replaces their real number with a different one. The FCC explains how spoofing and caller ID display work.
So before you try anything, look at the exact label your phone showed. Different labels need different tools.
*67 is a code callers dial before a number to hide their outgoing caller ID. If someone dials *67 before calling you, your phone shows "No Caller ID" or "Private Number."
*67 is a tool for the person calling, not for you. You cannot dial it to reveal who called.
Real callers with a legitimate reason to reach you usually leave a voicemail. Scammers often hide or fake their number. That's a spoofing or blocking tactic, and it is why a number on your screen is never proof of who is calling.
The method that works depends on your phone and the label you saw. Here is who each option is for:
Each method is covered below.
Carrier-level tools are your first move after an unwanted call. They need no app and work through the network that carried the call.
Step 1: Check your call log. For everyone.
Open your recent calls and look at the entry. Some calls show a number even when the name is missing. If a number appears, you can search it later. If the entry says "Unknown Caller" or "No Caller ID," move on to the next step.
Step 2: Try *69 right after the call. For US and Canada landline users.
*69 is a North American code, used mainly from landlines. It can read out the last number that called you or dial it back. Availability and any fee depend on your carrier, and many mobile carriers do not support it. WOW explains how Call Return works. Try it soon after the call, since the record may not last.
If the call showed "Unknown Caller," *69 will likely tell you the number is unavailable. That tells you the network data was missing.
Step 3: Dial *57 if the call was threatening or harassing. For US and Canada landline users.
*57 does not tell you the number. It sends a trace to your carrier, which holds the record for police. You will hear a confirmation if the trace was accepted. Some carriers charge for each successful trace. AT&T explains Call Trace. Use it when a call crosses a line: threats, repeated harassment, or anything that may need a police report. It is not for satisfying curiosity about who called.
Dial *57 before you call anyone else. It works on the most recent call only.
Step 4: Dial 1471 if you are in the UK. For UK landline users.
Dial 1471 after the call to hear the last caller's number. Whether it works depends on your phone provider. If the caller withheld their number, 1471 tells you so and gives no number. For caller display options and phone-company services, see Ofcom's guide to services that can help tackle nuisance calls. To report scam calls and learn about protections, see Ofcom's page on protecting yourself from scam calls and texts.
Step 5: Ask your carrier about its spam and blocking tools. For mobile users.
Most mobile carriers offer free tools that label suspected spam or block it. Contact your carrier or check your account to see what is on offer. If you need call records for a police report, ask your carrier what it can share. Some carriers need a formal request from law enforcement before they release details.
If the call came from an international line or an internet-based phone system that dropped its ID data, even carrier records may show nothing useful.
For iPhone and Android users. Your phone has built-in tools that filter unknown callers before they reach you. They do not reveal who called after the fact, but they cut down how often you deal with the problem.
On iPhone:
On iOS 26, go to Settings, then Apps, then Phone, and find Screen Unknown Callers. Choose Ask Reason for Calling, which asks the caller to say who they are before your phone rings, or Silence, which sends them to voicemail. On older versions, the setting is Silence Unknown Callers in the same place. Either way you still see the missed call and can check the voicemail before you call back.
The trade-off: this also silences real calls from doctors' offices, delivery drivers, and anyone you have not saved. Check your voicemail often if you turn it on.
None of these settings identify anyone. A scammer using a fake local-looking number can still ring through.
On Android:
Open your phone's Phone app, tap the three-dot menu, then open Settings and look for the caller ID and spam options. Turn on the built-in spam filter if your phone offers one. Flagged calls can go to voicemail without ringing. Menu names vary by phone maker.
The same trade-off applies. A spam filter can catch calls you want, so check your voicemail regularly.
Neither platform gives you a name or number for a call that arrived with no data. These settings just cut the noise so the calls worth investigating stand out.
For anyone willing to accept a privacy trade-off.
Caller ID apps match incoming numbers against a database of reported callers and flag known spam. They work best when a number did show up but you do not recognize it. They are much less useful when the call arrived with no number at all, because there is nothing to match.
Here is the trade-off: many caller ID apps upload your contact list to work. That means your friends' and family's numbers end up on someone else's servers. Read what an app collects before you install it, and skip any app that asks for more than it needs.
Some apps claim they can reveal numbers that callers hid on purpose. Treat those claims with care. They cannot recover data the network never sent, so they do nothing for a true "Unknown Caller" label.
Manual reverse lookup is the free fallback for any number that did appear on your screen. Paste the number into a search engine and add "scam" or "who called." Public reports from other people often show up. You may find others received the same call and already named the source.
If every method comes back empty, the call most likely came from an international line or an older internet-based phone system that never sent ID data.
Most unknown calls are mass-dialed attempts, not targeted threats. Scammers dial huge lists and wait for anyone to pick up. Answering tells them your number is active, which can bring more calls.
Follow these rules:
Real banks, agencies, and delivery services never demand that you act fast, confirm personal details, or call a different number. Treat any call that does as a red flag. That's a pressure scam.
If a call was harassing or fraudulent, you can file a complaint with the FCC through its spoofing guide.
Rarely. These calls often cross networks that do not pass caller ID data in a format your carrier can read. Codes like *69 and *57 depend on that data being there. When it is missing, carrier tools return nothing useful. Write down the date, time, and any number that did appear, then report the call to the FCC if it was harassing or fraudulent.
Yes, with trade-offs. On iPhone, Screen Unknown Callers (Silence Unknown Callers on older versions) can send numbers not in your contacts to voicemail. On Android, your phone's built-in spam filter can send flagged calls to voicemail. Both settings also catch real calls from doctors' offices, delivery services, and anyone you have not saved. Check your voicemail often so you do not miss calls that matter.
It depends on your carrier. *69 is a North American code used mainly from landlines, and many mobile carriers do not support it. Any fee also depends on the carrier. If it does not work, check your call log and ask your carrier about its spam and blocking tools instead.
No. *57 does not show you the number. It sends a trace to your carrier, and the record is held for police. Use it only for threatening or harassing calls, and dial it right after the call. Then report the calls to your local police.
Dial *57 from a landline right after the call to start a carrier trace. Then report it to your local police and file a complaint with the FCC through its spoofing guide. Keep a log of every call: date, time, what was said, and any number that appeared. Do not engage with the caller or call back from your main number. If it keeps up, ask your carrier about blocking options. If you feel in danger, visit flggd.com/emergency.
"Unknown Caller" means the network lost the caller's ID data. "No Caller ID" means the caller hid it. That difference decides which tools can help. Check your call log first, then use carrier codes from a landline or your carrier's spam tools on mobile. When the data never arrived, no tool can recover it.
If a number did appear, search it before you call back. If the call was threatening, dial *57 and document everything for police. Real callers leave a voicemail, and real organizations never rush you.
Unknown calls often come with a follow-up text or voicemail link. That message is where the scam usually lives. Before you click or reply, paste it into the Flggd checker at flggd.com/check. You get a verdict, the scam type, and what to do next. No account needed.
