ช่วยแนะนำโค้ดที่แสดง Mac address บนมือถือหน่อยครับ

<?
function macaddress() {
     $output = Array();
     exec( 'nbtstat -A '.$_SERVER['REMOTE_ADDR'], $output );
     $reg = '([a-f0-9]{2}\-){5}([a-f0-9]{2})';
     for( $a = 0, $b = &count( $output ); $a < $b; $a++ ) {
          if( preg_match( "/(?i){$reg}/", $output[$a] ) == true ) {
                return preg_replace( "/(?iU)(.+)({$reg})(.*)/", "\\2", $output[$a] );
          }
     }
     return 'No Mac Address';
}
echo"Mac address=".macaddress();
?>