How Rangecheck reads the Ofcom numbering register

Rangecheck publishes the figures on each page from Ofcom’s numbering files. The snapshot was published 14 Oct 2026 and fetched 2026-10-17 20:56 UTC. Release fc227d9e. Weekly folders are named by the fetch day.

Source files and verdict method

Every displayed data fact is tied to a source snapshot, a deterministic algorithm version and a claim identifier.

Input is normalised locally, matched to the longest valid block prefix, checked against the expected number length and mapped to a status-specific verdict. Identical records from different sources are deduplicated; equal-length matches use source-file code-point order. Claim states are active, superseded or retracted; corrections are recorded in the claim registry.

When a number is ported to another network, Ofcom’s files still list the original range holder of its block: ownership of the range does not move with the number. Rangecheck shows the range holder, not the network that serves a particular number today.

In the CSV files, numbers of one million or more are written with thousands separators, so that no value reads as a telephone number; smaller numbers are plain integers.

How to cite

Cite a Rangecheck page with the release and the day you read it. Use the title of that page, not a shortened label.

Rangecheck, “[page title] — Ofcom numbering snapshot published 14 Oct 2026”, release fc227d9e, https://rangecheck.co.uk[path], retrieved 24 Sep 2026. Contains Ofcom copyright material: numbering data (ofcom.org.uk).

B pages for area codes, range holders, number families and number blocks link here. The number you check is not part of a citation: it stays in your browser.

Block capacity

Block capacity is 10 to the power of the digits a block leaves free. A 0161 number is 11 digits long, counting the leading zero; without the zero, 10 digits remain. The block 1614 96 fixes 6 of those 10 digits, so 4 are free: 10 to the power of 4, which is 10,000 numbers. Blocks for shorter numbers hold fewer: the 8-digit freephone number 0800 1111 is a block of its own that holds one number, which is why some totals end in 1.

The same rule is used for every count of allocated numbers on this site. A block is one row of the Ofcom file. Two blocks can cover different numbers of telephone numbers.

Status glossary

Definitions below are Ofcom’s, word for word from the numbering-plan readme. Two statuses the readme does not define are listed with that note.

Ofcom, “Information on the UK National Telephone Numbering Plan” (readme.txt), issue 5 April 2004, retrieved 25 Sep 2026: https://static.ofcom.org.uk/static/numbering/readme.txt · Ofcom, “Review of the General Conditions of Entitlement”, statement, 26 March 2018 · Ofcom, “Code of Practice for numbers in ‘closed’ ranges”: https://www.ofcom.org.uk/phones-and-broadband/phone-numbers/number-cop-closed

Quarantined and Allocated (Closed Range) appear in the weekly files but are not defined in the readme quoted above; their rows say so and describe only what the files show.

Weekly fetches

Rangecheck publishes the figures on each page from Ofcom’s numbering files. The snapshot was published 14 Oct 2026 and fetched 2026-10-17 20:56 UTC. Release fc227d9e. Weekly folders are named by the fetch day.

Ofcom’s publication date is the date printed on each page. The folder name is the day the file was fetched, which can be the day after publication.

Changes to this method

• 24 Sep 2026 — allocated numbers are counted by block capacity (10 to the power of number length minus one minus the digits in the block) instead of register rows; area-code pages name the places from Ofcom’s area-code table; codes with no allocated blocks are shown as not allocated.
• 25 Sep 2026 — range-holder, number-family, number-block and hub pages publish per-page CSV files; weekly change counts use distinct blocks, not events; Ofcom status definitions are quoted word for word from its readme.
• 25 Sep 2026 — tables of recorded allocation years gained a “No recorded date” row, so each table adds up to the blocks it describes; the CSV files of release 6d60d6b0 for the affected pages were re-issued with that row.

Source detail