Fandt det her ved at google lidt.
<?
 // Because this script sends out HTTP header information, the first characters in the file must be the <? PHP tag. 
  $htmlredirect = "/html/my_htmlpage.asp";                          // relative URL to your HTML file
  $wmlredirect = "
http://wap.mysite.com/wml/my_wmldeck.wml";         // ABSOLUTE URL to your WML file 
  if(strpos(strtoupper($_SERVER['HTTP_ACCEPT']),"VND.WAP.WML") > 0) {  // Check whether the browser/gateway says it accepts WML.
    $br = "WML";
  }
  else {
    $browser=substr(trim($_SERVER['HTTP_USER_AGENT']),0,4);
    if($browser=="Noki" ||            // Nokia phones and emulators
      $browser=="Eric" ||            // Ericsson WAP phones and emulators
      $browser=="WapI" ||            // Ericsson WapIDE 2.0
      $browser=="MC21" ||            // Ericsson MC218
      $browser=="AUR " ||            // Ericsson R320
      $browser=="R380" ||            // Ericsson R380
      $browser=="UP.B" ||            // UP.Browser
      $browser=="WinW" ||            // WinWAP browser
      $browser=="UPG1" ||            // UP.SDK 4.0
      $browser=="upsi" ||            // another kind of UP.Browser ??
      $browser=="QWAP" ||            // unknown QWAPPER browser
      $browser=="Jigs" ||            // unknown JigSaw browser
      $browser=="Java" ||            // unknown Java based browser
      $browser=="Alca" ||            // unknown Alcatel-BE3 browser (UP based?)
      $browser=="MITS" ||            // unknown Mitsubishi browser
      $browser=="MOT-" ||            // unknown browser (UP based?)
      $browser=="My S" ||                       // unknown Ericsson devkit browser ?
      $browser=="WAPJ" ||            // Virtual WAPJAG 
www.wapjag.de      $browser=="fetc" ||            // fetchpage.cgi Perl script from 
www.wapcab.de      $browser=="ALAV" ||            // yet another unknown UP based browser ?
      $browser=="Wapa")                         // another unknown browser (Web based "Wapalyzer"?)
        {
        $br = "WML";
    }
    else {
      $br = "HTML";
    }
  } 
  if($br == "WML") {
    header("302 Moved Temporarily");       // Force the browser to load the WML file instead
    header("Location: ".$wmlredirect);
    exit;
  }
  else {
    header("302 Moved Temporarily");       // Force the browser to load the HTML file instead
    header("Location: ".$htmlredirect);
    exit;
  }
?>