How we verify data

Primary datasets

Every numbering fact on this site is derived mechanically from four public NANPA files, retrieved on July 29, 2026 (NANPA file date July 28, 2026):

Primary datasets used by this site
DatasetWhat it provides
NPA Database (CSV)Every area code: type, location, time zone, service dates, overlay complexes, jeopardy status, dialing plans
CO Code Assignment RecordsEvery active NPA-NXX prefix: code holder, OCN, rate center, pooling status, assignment dates
NPA Rate Center ReportRate center full names, LATA, FCC top-100 MSA membership, pooling status
NPA Exhaust Projections (2026-1)Projected exhaust dates per NPA complex

Rules

What we deliberately leave out

Fields that cannot be sourced from official data are omitted rather than approximated: county coverage per rate center (not part of NANPA's public files), wireline/wireless splits per code (not published at that granularity), and anything about individual subscribers (not public data at all, and out of scope by design). Where a page type depends on data that does not exist — per-prefix tables for toll-free codes, for example — the page says so explicitly.

Update cycle

NANPA refreshes its public reports daily; exhaust projections are published semi-annually. We regenerate the site from fresh copies of all four files with each content update, and the "current as of" date on each page moves accordingly.