$re = '/^(?:(\+[0-9]{1,3})[ -])?\(?\d{3}\)?[- ]?\d{3}[- ]?\d{4}/im';
$str = '1234567890
123-456-7890
(123)456-7890
123 456 7890
+1 123 456 7890
+123 123 456 7890
+1234 123 456 7890
+23 (123) 456-7890
+23 (123) 123-456-7890';
preg_match_all($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