$re = '/^\s*(?:\+?(\d{1,3}))?[-. (]*(\d{3})[-. )]*(\d{3})[-. ]*(\d{4})(?: ?x(\d+))?\s*$/m';
$str = '18005551234
1 800 555 1234
+1 800 555-1234
+86 800 555 1234
1-800-555-1234
1 (800) 555-1234
(800)555-1234
(800) 555-1234
(800)5551234
800-555-1234
800.555.1234
800 555 1234x5678
8005551234 x5678
1 800 555-1234
1----800----555-1234';
preg_match_all($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