$re = '/^[0]{1}[7]{1}[01245678]{1}[0-9]{7}$/m';
$str = '0712912826
0700000000
0710000000
0721234567
0731234567
0791234567';
preg_match_all($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