$re = '/\b0?\d{3}\s\d{3}\s\d{3}\b/m';
$str = 'x1: "Phone 18020210 914 171 717 mailbox 43, 1003 Florvaag"
Ex2: "Phone 18020210 N 0914 171 717 mailbox 43, 1003 Florvaag"
Ex3: "Phone 18020210 N0914 171 717 mailbox 43, 1003 Florvaag"';
preg_match_all($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