$re = '/(\+44)?\s?\(?0?\d{1,5}\)?\s\d{1,7}\s{0,1}\d{0,6}(?:\s-\s|\s)\s{0,2}\d{0,6}|(\+44)?\s?\(?\d{1,5}\)?\s\d{1,7}\s{0,1}\d{0,4}\s{0,1}\d{0,4}|(\+44)?\s?\(\d{1,5}\)\s?\d{3,7}\s?\d{0,4}\s?\d{0,4}|\d{4,5}\s*\d{3,5}\s\d{3,4}
/';
$str = '020 7738 3021 fdf';
preg_match($re, $str, $matches, PREG_OFFSET_CAPTURE, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php