PHP OS mobile detection with url redirect

OSMobileRedir.php

/* Zilli 201102
To detect the OS mobile system on the client device, 
match the value of $_SERVER[‘HTTP_USER_AGENT’],
then redirect to mobile url with the header php function. 
*/

<?PHP
function mobileDevice()
{
$type = $_SERVER[‘HTTP_USER_AGENT’];
if(strpos((string)$type, “Windows Phone”) != false || strpos((string)$type, “iPhone”) != false || strpos((string)$type, “Android”) != false)
return true;
else
return false;
}
if(mobileDevice() == true)
header(‘Location: http://index-mobile.html‘);
?>