$re = '/\+?(\d{1,2}|1\-\d{1,3}|0)+(3[2-9]|5[6|8|9]|9[]|8[1-9]|7[0|6-9])+([0-9]{7})/m';
$str = '0342138303
+84342138303';
preg_match_all($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