Validate a UK mobile number (2026 guide)

Validating a UK mobile number sounds trivial — does it start with 07 and have 11 digits? — but a real validator needs to handle the 07 vs 070 distinction, recognise legacy pager and personal-numbering ranges, and reject numbers from blocks that aren't allocated for mobile service. This guide shows the manual rules, the libphonenumber-js code, and the right tool for bulk validation.

#What counts as a UK mobile number

#Manual UK mobile validation rules

1. Strip non-digits except a leading +.
2. If the number starts +44, replace with 0.
3. If the number now has length 11 and starts 07, continue. Otherwise reject.
4. If the second-and-third digits are 0 or 6, reject (070 = personal-numbering, 076 = pager).
5. Optionally: cross-reference against the Ofcom range data to confirm the block is Allocated.

#Programmatic UK mobile validation in JavaScript / TypeScript

import { parsePhoneNumberFromString } from "libphonenumber-js/min";

export function isValidUkMobile(input: string): boolean {
  const phone = parsePhoneNumberFromString(input, "GB");
  if (!phone || !phone.isValid() || phone.country !== "GB") return false;
  return phone.getType() === "MOBILE";
}

export function toMobileE164(input: string): string | null {
  return isValidUkMobile(input)
    ? parsePhoneNumberFromString(input, "GB")!.number
    : null;
}

getType() returns MOBILE only for the actual mobile prefixes (071–075, 077–079). 070 personal-numbering returns PERSONAL_NUMBER; 076 pager returns PAGER. That distinction is what hand-rolled regexes miss.

#Validating in Python

import phonenumbers
from phonenumbers import PhoneNumberType

def is_valid_uk_mobile(value: str) -> bool:
    try:
        n = phonenumbers.parse(value, "GB")
    except phonenumbers.NumberParseException:
        return False
    if not phonenumbers.is_valid_number(n):
        return False
    return phonenumbers.number_type(n) == PhoneNumberType.MOBILE

#Validating in PHP / Laravel

use libphonenumber\PhoneNumberUtil;
use libphonenumber\PhoneNumberType;

function isValidUkMobile(string $value): bool {
    $util = PhoneNumberUtil::getInstance();
    try {
        $n = $util->parse($value, 'GB');
    } catch (\Exception $e) {
        return false;
    }
    return $util->isValidNumber($n)
        && $util->getNumberType($n) === PhoneNumberType::MOBILE;
}

#Carrier-aware validation — when format-check isn't enough

Format validation only tells you the number *could* be a real mobile. To find out whether it's *actually in service*, you need a carrier-aware API:

For consumer apps that just need 'is this number well-formatted?', stick with libphonenumber-js — it's free and runs locally. For B2B applications where you're cleansing thousands of numbers, the carrier-aware APIs justify their cost. We cover the comparison in UK phone number validation API.

#Validating mobile numbers for SMS marketing

If you're validating numbers for an SMS marketing list, three extras you need:

1. Lawful basis — UK PECR + GDPR require opt-in (with very limited soft-opt-in exceptions). Validation alone doesn't grant consent.
2. Number type = MOBILE — landlines can't receive SMS; sending to one wastes credits and triggers carrier complaints.
3. Currency check — numbers can be ported between MNOs. Carrier-aware APIs catch ported numbers; pure format checks don't.

#Bottom line

Validating a UK mobile number is two layers: a format check (libphonenumber-js, free, runs locally) and an in-service check (carrier-aware API, paid, runs over the network). Use the first for every signup form; add the second for bulk CRM cleansing or SMS marketing.