function getBrowser($agent) {
 $browser = array(
  "MSIE 5.0" => "/msie 5.0[0-9]*/",
  "MSIE 5.5" => "/msie 5.5[0-9]*/",
  "MSIE 6.0" => "/msie 6.0[0-9]*/",
  "MSIE 7.0" => "/msie 7.0[0-9]*/",
  "MSIE 8.0" => "/msie 8.0[0-9]*/",
  "MSIE 9.0" => "/msie 9.0[0-9]*/",
  "Chrome" => "/chrome\/*/",
  "FireFox" => "/firefox\/*/",
  "Netscape" => "/x11/",
  "Opera" => "/opera*/",
  "Safari" => "/safari\/*/",
  "Android" => "/android/",
  "Mobile Safari" => "/mobile\/[0-9a-z]* safari/",
  "Robot" => "/yahoo/",
  "Robot" => "/bot/"
 );
 $agent = strtolower($agent);
 foreach($browser as $name=>$exp){
  if(preg_match($exp, $agent)){
  $browser = $name;
  }
 }
 return $browser;
}

$u_agent = $_SERVER['HTTP_USER_AGENT'];
$browser =  getBrowser($u_agent);
if($browser == 'Android' || $browser == 'Mobile Safari'){
 if($browser == 'Android'){
  ECHO "ANDROID";
 }else{
  ECHO "IPHONE";
 }
}else{
 ECHO "OTHER";
}