$re = '/^612\s?[1-5]0\s?0(?:[0-5]\d|6[0-4])\s?0000\s?(?:[0-5]\d|6[0-4])\s?00\s?\d{4}$/m';
$str = '61230005000055001234
612 30 005 0000 55 00 1234';
preg_match_all($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