PhoneCheck
Look up any phone number against the published numbering plans — country, type, region and prefix.
This number is not sent anywhere. The numbering plans ship with the page and the check runs on your device. Looking up a region or carrier fetches one prefix table for the country calling code — the same file every visitor checking that country asks for, which reveals nothing about your number. Nothing is stored, and there is no account.
Private by design. This tool runs entirely in your browser. Your input is processed on your own device and is not uploaded by DO101.
About the PhoneCheck
Paste a phone number and see what the world's published numbering plans say about it: which country issued the calling code, whether the range is mobile, landline, VoIP or premium rate, which numbering region the prefix belongs to, and which network it was originally allocated to. Every line says where it came from, so you can tell a fact from an indication. There is no spam database and no scam verdict here — those cannot be done honestly by a free tool, and a valid, ordinary number is what most scam calls come from anyway. The whole check runs on your device; the number is never sent to DO101.
How to use it
- 1Type or paste the phone number, ideally starting with + and the country code.
- 2No + in the number? Pick the country it came from so there is a numbering plan to read it against.
- 3Press Check number. Everything runs on your device.
- 4Read the cards: each one says whether it is Verified, Information or Unknown.
- 5Read the observations and the safety guidance, then copy the results if you are reporting the call.
What you get
- Detects the country automatically from the international prefix
- Validates and normalises the number to E.164, international and national formats
- Mobile, landline, VoIP, freephone and premium rate, where the plan publishes it
- Numbering region and original carrier from Google's libphonenumber prefix tables
- Every result labelled Verified, Information or Unknown — never a guess dressed up as a fact
- Local rule-based checks for unallocated prefixes, premium ranges and placeholder patterns
- Says “Unknown / not available” rather than inventing a carrier or a location
- Copy the whole result as text for a fraud report
- No account, no database, no API keys, and the number is never sent to DO101
How to check a phone number
Six steps, in the order that actually protects you. The lookup is the first one, and the least important.
- 1Start with the + and the country codeA number without one is ambiguous: 0312345678 is a Tokyo landline in Japan and nothing at all in most other countries. With +81 in front there is no guesswork left, which is why the checker detects the country from the prefix before anything else.
- 2Check the range, not the numberThe numbering plan can tell you the range exists and what it is for. It cannot tell you the line is connected, and no public data can. Treat “valid” as “this could be a real number”, never as “this is a real caller”.
- 3Look at what the call costs youPremium rate and satellite ranges are the ones where the number itself is the scam, because ringing back is what makes the money. Those are visible in the numbering plan, so the checker flags them outright.
- 4Assume the caller ID may be someone else'sSpoofing a number takes minutes and no special access. If a call claims to be your bank, the displayed number matching the bank's real line tells you nothing — the scam depends on exactly that.
- 5Verify by calling back on a number you sourced yourselfThe back of your card, the official website, your last statement. Not the number that called, not one in the message. This single habit defeats nearly every impersonation call, whatever the lookup said.
- 6Report it through your phone, not a websiteBlocking and reporting in the call log feeds your network's own filtering, which is what actually stops the next call. Then tell the organisation being impersonated and your national fraud line.
What a phone number cannot tell you
Most phone-lookup sites answer these anyway. This one lists them so you know what the silence means.
Who owns the number
Subscriber records are not public. Anywhere that claims otherwise is recycling scraped personal data or inventing it.
Where the phone is
The numbering region is where the prefix is issued. The handset can be anywhere on earth, and nothing here asks for or estimates a position.
Whether the line is connected
The plan says a range is allocated, not that a particular number is in service. Only ringing it tells you that.
Whether a call was really from it
Caller ID is supplied by the caller's system and is not verified end to end. A displayed number is a claim, not evidence.
How many people reported it
There is no spam database here. A free browser tool cannot host one honestly, and the sites that claim to are mostly guessing.
The current network
The carrier table names who the range was originally allocated to. Number portability moves numbers between networks and no public dataset follows them.
The data behind the answers
Every fact on this page comes from Google’s libphonenumber, the open numbering-plan library that phones, CRMs and telecoms software use. It is the same data your handset uses to decide a number is dialable.
The numbering plans reach the page through libphonenumber-js (MIT). The numbering-region and carrier prefix tables are libphonenumber’s own geocoding and carrier resources (Apache 2.0), repackaged by libphonenumber-geo-carrier (MIT) and converted to JSON at build time, split by calling code so a lookup fetches one small file. No value is added, removed or edited on the way. Both licences travel with the data at /phone-data/NOTICE.txt.
Nothing else is consulted. There is no spam database, no reverse-lookup service and no paid API — which is why the tool is free, and why it says “Unknown / not available” instead of filling a gap with something plausible.
Where the number goes
Nowhere. The numbering plans are bundled into the page, so parsing, validation, type detection and every risk rule run on your own device.
The one thing fetched is a prefix table for the country calling code — a static file like /phone-data/geocodes/81.json, identical for everyone checking a Japanese number, so the request says nothing about which number you typed. Nothing is logged, nothing is stored, nothing is sent to a third party, and there is no account to make. A phone number is personal data; treating it as something to keep would be the wrong design, so there is nowhere for it to be kept.
Reporting a nuisance call? Our privacy policy covers the rest of the site.
Frequently asked questions
Can this tell me if a number is a scammer?
No, and nothing can from the number alone. What it can tell you is what the number is — whether the range exists, what it is for, and whether it costs extra to ring. Most scam calls come from perfectly valid, ordinary numbers, and a great many display a number that is not really theirs. Treat the result as background, and judge the call by what is being asked of you.
Can I find out who owns a number?
Not here. Subscriber details are not public anywhere in the published numbering data, and sites that claim to have them are either recycling scraped personal information or making it up. DO101 will not do either.
Can it show where the phone is right now?
No, and no honest tool can. The numbering region tells you where a prefix is issued — a number issued in Osaka answers just as well in Berlin. Nothing on this page asks for, receives or estimates a live position, and the industry systems that can locate a handset are available to emergency services, not to websites.
Where does the data come from?
Google's libphonenumber, which is the open numbering-plan library that phones and telecoms software use. The plans come from libphonenumber-js (MIT), and the region and carrier prefix tables are libphonenumber's own geocoding and carrier resources (Apache 2.0), converted into JSON at build time. The licences ship alongside the data at /phone-data/NOTICE.txt.
Why is the carrier often “Unknown”?
The carrier tables cover mobile allocations, and not every country publishes them, so landlines and many regions have no entry at all. Where there is one it names the network the range was originally given to — number portability means the number may have moved since, and no public dataset tracks that. Showing “Unknown / not available” is the honest answer, so that is what it shows.
What do Verified, Information and Unknown mean?
Verified means the published numbering plan states it — the country of a calling code, the digit lengths a plan allows, whether a range is allocated. Information means the data is real but indicative, like the numbering region or the carrier at allocation, both of which go stale. Unknown means the bundled data has nothing, and the tool says so instead of guessing.
Why does a number I know is real show as invalid?
Usually one of three things: a digit is missing or extra, the country code is absent and the wrong country was assumed, or the range is genuinely reserved. Numbers in the drama ranges regulators set aside for films and examples, such as 555-0100 to 555-0199 in North America, are invalid by design and the tool says so. Very new operator ranges can also take a while to reach the published plan.
Is the number sent to a server?
No. The numbering plans are bundled into the page, so the parsing, validation and risk rules all run in your browser. Looking up a region or carrier fetches one static prefix table for the country calling code — the same file for everyone checking that country, which says nothing about your number. There is no upload, no log and no account.
I got one missed call from an international number. Should I ring back?
No. That is the whole shape of the wangiri scam: one ring from a premium-rate or satellite range, and the charge starts the second you return the call. Paste the number here — if the calling code is a global service code or the range is premium rate, the check will say so. If it was someone genuine, they will call again.
Does it work for Japanese, US and Indian numbers?
Yes, and for every other country libphonenumber covers, which is all of them. Local formats are understood too: a Japanese number typed as 03-1234-5678 works once you pick Japan, as does an Indian 98765 43210 or a US (202) 555-0143. Starting with + is simplest, because then the country is read straight from the number.
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