$re = '/^\d{2}-\d{7}$|\d{9}|\d{3}(?<sep>[-\s])\d{2}\k<sep>\d{4}/m';
$str = '12-3456789
123456789
123 45 6789
123-45-6789';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($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