$user_agent = $_SERVER['HTTP_USER_AGENT'];

    $ipod = strpos($user_agent,"iPod");

    $iphone = strpos($user_agent,"iPhone");

    $android = strpos($user_agent,"Android");

    $symb = strpos($user_agent,"Symbian");

    $winphone = strpos($user_agent,"WindowsPhone");

    $wp7 = strpos($user_agent,"WP7");

    $wp8 = strpos($user_agent,"WP8");

    $operam = strpos($user_agent,"Opera M");

    $palm = strpos($user_agent,"webOS");

    $berry = strpos($user_agent,"BlackBerry");

    $mobile = strpos($user_agent,"Mobile");

    $htc = strpos($user_agent,"HTC_");

    $fennec = strpos($user_agent,"Fennec/");

if ($ipod || $iphone || $android || $symb || $winphone || $wp7 || $wp8 || $operam || $palm || $berry || $mobile || $htc || $fennec) {

echo 'Содержимое для мобильников';

} else {

echo 'Для компов';

}