asp için:
if (Request.Headers["User-Agent"] != null && (Request.Browser["IsMobileDevice"] == "true" || Request.UserAgent.ToUpper().Contains("MIDP") || Request.UserAgent.ToUpper().Contains("CLDC") || Request.UserAgent.ToLower().Contains("iphone") || Request.UserAgent.ToLower().Contains("avant") || Request.UserAgent.ToLower().Contains("nokia") || Request.UserAgent.ToLower().Contains("pda") || Request.UserAgent.ToLower().Contains("moto") || Request.UserAgent.ToLower().Contains("windows ce") || Request.UserAgent.ToLower().Contains("hand") || Request.UserAgent.ToLower().Contains("mobi") || Request.UserAgent.ToUpper().Contains("HTC") || Request.UserAgent.ToLower().Contains("sony") || Request.UserAgent.ToLower().Contains("panasonic") || Request.UserAgent.ToLower().Contains("blackberry") || Request.UserAgent.ToLower().Contains("240x320") || Request.UserAgent.ToLower().Contains("voda")))

{

Response.Redirect("yourpage.aspx");

}


php için:
<? if (
stristr($ua, "Windows CE") or
stristr($ua, "AvantGo") or
stristr($ua,"Mazingo") or
stristr($ua, "Mobile") or
stristr($ua, "T68") or
stristr($ua,"Syncalot") or
stristr($ua, "Blazer") ) {
$DEVICE_TYPE="MOBILE";
}
if (isset($DEVICE_TYPE) and $DEVICE_TYPE=="MOBILE") {
$location='mobile/index.php';
header ('Location: '.$location);
exit;
}
?>

falan
fakat çok fazla telefon user agenti olduğu için hepsnin bulunduğu bi liste bulup düzgün ve uzuncana bir kontrol hazırlamak lazım..