UK Phone Number

Detects UK national telephone numbers per Ofcom's National Telephone Numbering Plan: geographic numbers (01/02 prefix) and mobile numbers (07 prefix, second digit restricted to 1-5 or 7-9 to exclude 070 personal-numbering and 076 pager ranges), both as 11-digit domestic strings (leading 0 + 10 significant digits), plus the +44 international form (10 significant digits, leading 0 dropped per ITU/Ofcom convention). Digit groups after the initial prefix use a flexible per-digit optional separator rather than a single fixed grouping, because Ofcom's numbering plan allows multiple valid group-length conventions (4+6, 3+7, 2+8, 5+5) that vary by area. Non-geographic service numbers (03/08/09) are intentionally out of scope — they are typically organizational/service numbers rather than personal PII, mirroring how au-fixed-line-telephone scopes to geographic numbers only.

Type: regex
Engine: universal
Confidence: medium
Confidence justification: Medium confidence: the geographic (01/02) and mobile (07 with second-digit restriction) prefix constraints narrow the format, but UK numbers carry no checksum and an 11-digit UK-shaped domestic sequence still collides with other structured identifiers. Per the phone-family convention set by au-fixed-line-telephone (every tier requires positive corroborative evidence; high digit-collision formats never get a zero-evidence tier), both the domestic and +44 international sub-regexes are evidence-gated at every tier: 75 requires generic phone-context evidence and 85 requires country-specific phone keywords with template/noise exclusion. The literal +44 prefix improves precision when present but is not by itself sufficient gating.
Jurisdictions: uk
Regulations: UK GDPR, PECR
Frameworks: ISO 27001, ISO 27701, SOC 2
Data categories: pii, contact-information
Scope: narrow
Risk rating: 5
Platform compatibility: Purview: Compatible, GCP DLP: Unsupported, Macie: Unsupported, Zscaler: Compatible, Palo Alto: Unsupported, Netskope: Unsupported

Pattern

(?<!\d)(?:\+44[\s.-]?(?:[12][\s.-]?\d[\s.-]?\d[\s.-]?\d[\s.-]?\d[\s.-]?\d[\s.-]?\d[\s.-]?\d[\s.-]?\d[\s.-]?\d|7[\s.-]?[1-57-9][\s.-]?\d[\s.-]?\d[\s.-]?\d[\s.-]?\d[\s.-]?\d[\s.-]?\d[\s.-]?\d[\s.-]?\d)|0(?:[12][\s.-]?\d[\s.-]?\d[\s.-]?\d[\s.-]?\d[\s.-]?\d[\s.-]?\d[\s.-]?\d[\s.-]?\d[\s.-]?\d|7[\s.-]?[1-57-9][\s.-]?\d[\s.-]?\d[\s.-]?\d[\s.-]?\d[\s.-]?\d[\s.-]?\d[\s.-]?\d[\s.-]?\d))(?!\d)

Corroborative evidence keywords

phone, mobile, landline, call, text, contact number, UK phone number, call me on, cell, telephone, tel, dial, text me, text message, [object Object], WhatsApp, voicemail, phone number, mobile number

Proximity: 300 characters

Should match

Reception: 020 7946 0958 — Ofcom-reserved London geographic drama number (020 7946 0XXX range)
Call the office on 01632 960960 — Ofcom-reserved 01632 geographic drama number for areas without a specific reserved code
Mobile: 07700 900123 — Ofcom-reserved mobile drama number (07700 900XXX range)
Contact: +44 20 7946 0958 — International +44 form of the London drama number, leading 0 dropped

Should not match

0345 600 0000 — Non-geographic 03 service number — out of scope for this pattern (see description)
07000 123456 — 070 is personal-numbering, not mobile — second digit 0 is excluded from the mobile set
020 7946 095 — One digit short of the required 10 significant digits after the leading 0
4420794609589999 — Valid-shaped digit run embedded inside a longer reference number, rejected by digit boundaries

Known false positives

An 11-digit UK-shaped domestic sequence (geographic or mobile prefix, correct leading digits) can still coincidentally match invoice numbers, order numbers, or other structured identifiers of the same length and leading-digit distribution. Mitigation: Every tier — for both the domestic and +44 international sub-regexes — requires positive phone-context or country-specific evidence within 300 characters; no zero-evidence tier exists, so a bare digit run without corroborating context never fires at any confidence level.
The flexible per-digit separator allows unusual spacing patterns beyond the conventional group boundaries (e.g. a digit-by-digit hyphenated form), which slightly over-generalises acceptable formatting in exchange for covering Ofcom's multiple valid grouping conventions (4+6, 3+7, 2+8, 5+5). Mitigation: Corroborative evidence and noise-exclusion gating apply regardless of internal spacing; the structural leading-digit constraints are unaffected by separator placement.