Methodology and sources
Where NumberingData data comes from, how often it is refreshed, what it cannot tell you, and the known gaps.
What this site is built from
Every number on this site comes from one of three places, and each page names the ones it used with the date they were retrieved.
NANPA – the North American Numbering Plan Administrator. Two files:
the NPA Database (`npa_report.csv`), which lists every area code with its state or province, in-service date, overlay complex, dialing plan and relief-planning status;
and the CO Code Assignment Records, which list every assigned NXX number block with the carrier that holds it and its rate center.
These are the authoritative records of how North American phone numbering is allocated. Our copy was retrieved on 1 November 2026, when the NANPA files carried file date 11/01/2026.
FTC – Do Not Call Reported Calls Data. Daily files of consumer complaints, including the phone number shown in the caller ID. We aggregated 25 daily files covering 28 Sep – 30 Oct 2026 – 282,276 complaints.
Our own lookups and user reports. Line type and current carrier for an individual number come from a carrier-lookup API at the moment you search. User reports are submitted through this site and reviewed by a person before they appear.
What the numbers mean, and do not mean
Carrier share is share of number blocks, not of people. When a page says Verizon holds 86.9% of area code 212, that means Verizon was allocated 86.9% of the NXX blocks in that code. It does not mean 86.9% of people with a 212 number are Verizon customers – numbers move between carriers when people port them, and NANPA records do not track that.
Complaint counts are about spoofed caller IDs. Spam callers routinely fake the number they display, and a local-looking number gets answered more often. So when an area code ranks high in FTC complaints, the honest reading is that the code is imitated often. It is not evidence that the calls originate there, and it is not a judgement about people who have numbers in that code.
Rate centers are telephone geography, not places. In large metros the rate center is a zone code: Manhattan appears as NWYRCYZN01, Los Angeles as LSAN DA 01, Chicago as CHICGOZN01. We show these as NANPA records them rather than guessing at neighbourhood names. Smaller codes do give real place names, and we use them.
Known gaps, stated plainly
- The FTC complaint window is five weeks, not a year. The FTC publishes only about five weeks of daily files at a time. Every complaint figure on this site is for 28 Sep – 30 Oct 2026 and is labelled with that window. Longer history needs the FTC's API, which we have not yet pulled.
- Carrier pages are not published. Insurance deductibles, claim deadlines and support numbers have to be read off each carrier's own current terms. Until a person has verified a figure against the carrier's document, the page stays unpublished rather than carrying an estimate. A wrong deductible is a wrong answer about someone's money.
- Neighbourhood detail for big metros is missing, because of the rate-center zone codes described above. Mapping zones to neighbourhoods needs a source we do not have yet.
- Canadian coverage is thinner than US coverage. NANPA records Canadian codes but the CO Code Assignment files we use cover US states, so Canadian pages currently lack number-block and carrier detail.
How often this is refreshed
NANPA's files are regenerated daily and we re-import them weekly; an area code's page shows the date its data was verified. FTC files are published each weekday and we re-aggregate them weekly. Any page carrying a figure older than 45 days is pulled from the index until it is re-checked.
What we do not publish
We do not publish names, addresses or any attempt to identify who holds a phone number. A lookup here returns carrier, line type, region and complaint history – nothing that identifies a person. We are not a people-search service and we do not link to one.