UK phone number formatting to Ofcom specifications

Inside StackOverflow there are many pieces of code that have different phone numbers.

Most of them use the US phone number format. There are also a few that you can use for some rooms in the UK, but not all of them give the correct results.

The following code shows the UK phone numbers as follows:

Non-geographic numbers starting 03, 08 and 09 are formatted as 0xxx xxx xxxx and +44 xxx xxx xxxx.

Mobile phone numbers starting with 07 are formatted as 07xxx xxxxxx and +44 7xxx xxxxxx.

VoIP and other 05 numbers are formatted as 05xxx xxxxxx and +44 5xxx xxxxxx.

Numbers starting with 01 and 02 are geographical numbers. They have variable area code. To ensure accuracy, the latest Ofcom specifications were published at www.ofcom.org.uk/static/numbering/sabc.txt and www.ofcom.org.uk/static/numbering/codelist.zip.

Ofcom list 0113/0114/0115/0116/0117/0118 and 0121/0141 have a 3-digit zone code and 015242, 013873, 015394/015395/015396, 016973/016974, 017683/017684/017687 and 019467 as having a 5-digit area code. The rest uses a 4-digit area code. 0171 and 0181 were used to be 3-digit area codes in London, but are no longer used.

PHP code is easy to test with simple form-based input enabled. The form may be discarded if the code is used in any other way.

. , , , , , , , 10 . .

, "ext 234" "x 234".

, .

0800 1111 0845 4647. , 7 .

<?php

// format UK telephone numbers using Ofcom specifications
// www.ofcom.org.uk/static/numbering/sabc.txt
// www.ofcom.org.uk/static/numbering/codelist.zip



// parse submitted form variables

if (ISSET($_POST['tel_form']) && ($_POST['tel_form'] == "1")) {

  if (ISSET($_POST['tel_num'])) {

    $tel_num = $_POST['tel_num'];

    $text = '    <p><b>Number as input:</b> ' . $tel_num . "</p>\n";



// remove leading +44, 00 44, 011 44 if present

    $leadingPattern = '/^(\+|00|011)?\ ?44(.*)/';
    if (preg_match($leadingPattern, $tel_num, $leadingMatches)) {
      $tel_num = $leadingMatches[2];
    }



// remove and separately store any extension number

    $extPattern = '/((ext|x)(.*))/';
    if (preg_match($extPattern, $tel_num, $extMatches)) {
      $extension = $extMatches[1];
    }
    $extReplacements = '';
    $tel_num = preg_replace($extPattern, $extReplacements, $tel_num);



// remove all non-digit characters and punctuation

    $nonDigitPattern = '([^0-9]+)';
    $nonDigitReplacements = '';
    $tel_num = preg_replace($nonDigitPattern, $nonDigitReplacements, $tel_num);
    $extension = preg_replace($nonDigitPattern, $nonDigitReplacements, $extension);



// remove leading 0 if present

    $leadingZeroPattern = '/^0+(.*)/';
    if (preg_match($leadingZeroPattern, $tel_num, $leadingZeroMatches)) {
      $tel_num = $leadingZeroMatches[1];
    }



// check remaining number length is 10 digits long

    if (strlen($tel_num) < '10') {
      $text .= '    <p>' . 'Telephone number too short.' . "</p>\n";
    }

    elseif (strlen($tel_num) > '10') {
      $text .= '    <p>' . 'Telephone number too long.' . "</p>\n";
    }



// format valid numbers

    else {


// format 3 digit area code for 0113/4/5/6/7/8, 0121, 0141

      $length3pattern = '/^(1(1[345678]|[24]1))([0-9]{3})(.*)/';
      if (preg_match($length3pattern, $tel_num, $matches)) {
        $formatted_number = $matches[1] . ' ' . $matches[3] . ' ' . $matches[4];
      }



// format 5 digit area code for 015242, 013873, 015394/5/6, 016973/4, 017683/4/7, 019467

      $length5pattern = '/^(1(3873|5242|539[456]|697[34]|768[347]|9467))(.*)/';
      if (preg_match($length5pattern, $tel_num, $matches)) {
        $formatted_number = $matches[1] . ' ' . $matches[3];
      }



// format non-geographic numbers

      $NGNpattern = '/^([389][0-9]{2})([0-9]{3})(.*)/';
      if (preg_match($NGNpattern, $tel_num, $matches)) {
        $formatted_number = $matches[1] . ' ' . $matches[2] . ' ' . $matches[3];
      }



// format all other numbers

      if (!ISSET($formatted_number)) {
        $pattern = '/^([1257][0-9]{3})(.*)/';
        if (preg_match($pattern, $tel_num, $matches)) {
          $formatted_number = $matches[1] . ' ' . $matches[2];
        }


// else warn that number isn't valid

        else {
          $text .= "    <p>Telephone number probably not valid.</p>\n";
        }
      }



// store number in international and national formats

    }

    if (ISSET($formatted_number)) {

      $int_formatted_number = '+44 ' . $formatted_number;
      $text .= '    <p><b>International format:</b> ' . $int_formatted_number . "</p>\n";

      $codePattern = '/^([12][^\ ]+)(\ .*)/';
      if (preg_match($codePattern, $formatted_number, $matches)) {
        $nat_formatted_number = '(0' . $matches[1] . ') ' . $matches[2];
      }
      else {
        $nat_formatted_number = '0' . $formatted_number;
      }
      $text .= '    <p><b>National format:</b> ' . $nat_formatted_number . "</p>\n";

      if ((ISSET($extension)) && (!empty($extension))) {
        $text .= '    <p><b>Extension:</b> ' . $extension . "</p>\n";
      }

    }



// show start message for first time form use

  }
}
else {
  $text = "    <p><b>Please start by entering a UK telephone number.</b></p>\n";
}



// show HTML page with form for input
?>
<!DOCTYPE html>

<html>

  <head>

    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
    <title>UK telephone number formatter</title>

  </head>

<body>

<?php
if (ISSET($text)) {
  print $text;
}
?>

    <hr>

<?php
if ((ISSET($tel_num)) && (!empty($tel_num))) {
  $tel_num = '0' . $tel_num;
}
?>
    <form action="telnum.php" name="input" method="post">
      <p><b>Enter a UK telephone number to format:</b> <input type="text" name="tel_num" value="<?php print $tel_num; ?>" />
      <input type="hidden" name="tel_form" value="1" />
      <input type="submit" value="submit" /></p>
    </form>

  </body>

</html>