$re = '/[/+ #_;.-]?(?<![0-9])[0-9]{9,10}(?![0-9])/m';
$str = '12
123456789
1234567890
123456789/1234567890
123456789/1/123456789
123456789+1234567890
Order number: 6508955960_000010_1005500
';
preg_match_all($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