$re = '/^(1\s?)?(\d{6})?(\(\d{3}\)|\d{3})[\s\-]?\d{3}[\s\-]?\d{4}$/';
$str = '5555555555';
preg_match_all($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