US phone numbering landscape

Findings

• Of 205,160 central office codes in the file, 198,656 (96.8%) are assigned, 197,646 of those are in service, and 6,504 are not assigned to a carrier.
• Of the 197,646 in-service codes, 141,629 (71.7%) are pooled.
• The 1,425,850 thousands-blocks in the file split by status as AS 992,432, RT 318,993, AV 108,583, AP 3,613, AF 2,229; 988,006 assigned blocks sit inside in-service codes.
• 2,754 distinct company names hold the 197,646 in-service codes. The ten largest hold 52,048 (26.3%), led by T-MOBILE USA, INC. with 7,023.
• Among the 84,275 in-service codes that carry an assignment date, 2001 has the most (7,104) and 2009 the fewest (1,788) of the full years; 25,050 were dated from 2021 on.
• The NANPA area code table kept for the phone check holds 451 geographic area codes in service, 372 of them in the United States, and every one of those 372 also has rows in the central office code file.

Definitions

• Central office code: the first six digits of a ten-digit North American number, the area code (NPA) plus the exchange (NXX). The NANPA file lists one row per code. Prefix means the same thing on this page.
• Assigned: a code whose row in the NANPA file has the use value AS. Rows with another use value are counted as not assigned to a carrier.
• In service: an assigned code whose in-service column in the NANPA file reads Yes.
• Pooled: an in-service code whose pooled column in the NANPA file reads Y.
• Thousands-block: a run of 1,000 numbers inside a code (for example 555-0000 to 555-0999 inside one prefix). The block file lists each block with a status code, and this page counts the status AS as assigned.
• Holder: the company name the NANPA file gives for the operating company number (OCN) on a code row. Names are used exactly as written, so one corporate group can appear under several names.
• Assignment date: the date column of the code file. It is blank for many codes, so every count by year says how many codes carry a date.

Share of in-service central office codes held by each of the ten largest holders

• T-MOBILE USA, INC.3.55%
• NEW CINGULAR WIRELESS PCS, LLC - IL3.44%
• SOUTHWESTERN BELL3.02%
• QWEST CORPORATION2.84%
• PAETEC ITEL, LLC2.81%
• PACIFIC BELL2.48%
• NEW CINGULAR WIRELESS PCS, LLC - GA2.18%
• BELLSOUTH TELECOMM INC DBA SOUTHERN BELL TEL & TEL2.11%
• NEW CINGULAR WIRELESS PCS, LLC1.96%
• METROPCS, INC.1.94%

n = 197,646 assigned, in-service central office codes.

Thousands-blocks by status code

• AS69.6%
• RT22.4%
• AV7.6%
• AP0.3%
• AF0.2%

n = 1,425,850 thousands-blocks in the file.

Central office codes by state of the file

n = 205,160 central office codes, NANPA code report dated October 17, 2026.

Thousands-blocks by status code

n = 1,425,850 thousands-blocks, NANPA block file dated October 17, 2026.

Ten largest holders by in-service prefixes held

n = 197,646 assigned, in-service codes held by 2,754 distinct company names.

In-service codes by year of the assignment date

n = 84,275 in-service codes with a date (latest date August 26, 2026), so 2026 is a partial year. Codes without a date are left out.

Geographic area codes in service in the United States, top states

n = 372 United States geographic area codes, NANPA area code report dated 10/17/2026.

Method

1. Read the central office code table and the thousands-block table that LookValid builds from the two NANPA reports (code report dated October 17, 2026, block file dated October 17, 2026).
2. Counted codes by their use, in-service and pooled columns, and blocks by their status column, with no rows removed.
3. Grouped assigned, in-service codes by the company name stored for each code row's OCN, and ranked the groups by prefixes held. Names are not merged or classified.
4. Counted assignment dates by calendar year over in-service codes that have a date.
5. Counted geographic area codes from the NANPA area code report (file date 10/17/2026) and checked each United States area code for rows in the code file.
6. The script is in the downloads below. It only reads local files and does not download anything.

What this cannot show

• The script reads local tables that LookValid builds from the NANPA report files, and those tables are not part of the download. The script shows the method and the arithmetic, and the CSV holds every aggregate count used on this page.
• The files hold the carrier a block was originally assigned to. They do not show number porting, so they cannot say who serves a number today or whether a number is active.
• Company names are raw. A corporate group that appears under several names is counted as several holders, so the top ten shares are a floor for those groups, not a measure of group concentration.
• The assignment date is blank for many codes, so the year counts describe only the dated codes. They are not a count of every code ever assigned.
• The files used here carry no in-service date for area codes, no overlay complex and no parent area code. Area codes by in-service year, overlay codes versus original codes and area codes added since 2021 are therefore not reported.
• The files do not say which holders are wireless carriers, landline carriers or other business types, so no split by holder type is given.

Download the data and the script

• Aggregate counts (CSV) Counts only: code states, block statuses, the 25 largest holders, assignment years and area codes by country. No personal data.
• Script (Node) Reads the NANPA tables from the data folder and rewrites the data file and CSV.

Questions

Sources

• NANPA reports: central office code assignment report (North American Numbering Plan Administrator), file date October 17, 2026 https://reports.nanpa.com/, read 2026-10-18
• NANPA reports: thousands-block assignment report (North American Numbering Plan Administrator), file date October 17, 2026 https://reports.nanpa.com/, read 2026-10-18
• NANPA reports: NPA (area code) report (North American Numbering Plan Administrator), file date 10/17/2026 https://reports.nanpa.com/, read 2026-10-18

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Every figure above comes from open data or from a measurement run described in the method. LookValid puts the same kind of data behind one API key.