$re = '/^(8)[\s(-]{0,3}[0-9]{3}[\s)-]{0,3}[0-9]{3}[\s-]{0,3}[0-9]{2}[\s-]{0,3}([0-9]{2})$/u';
$str = '8-911-50-656-33';
preg_match($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