$re = '/"S":"(.*?)".*"IMEI":"(.*?)".*/m';
$str = '{"ID":"NOKIA-71E1","KY":"59ad728d99","U":"admin","P":"cfa522ec5a","S":"FSH21290288A","23S":"DC8D8A4171E1","N":"5G12-13W-A","PN":"3TG00799ABAA","IMEI":"352778340662308"}';
preg_match_all($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