title: Utility of HTTP header "Content-Type: application/force-download" for mobile?
body: <p>I am currently working on a PHP script that allows you to download media contents (video, audio, pictures...) from your mobile device by accessing a link. (i.e. <a href="http://www.my-web-site.com/download.php?id=7ejs8ap">http://www.my-web-site.com/download.php?id=7ejs8ap</a>)
  My script worked very vell when I was testing it with recent mobile (Samsung Galaxy S, iPhone 4S, some others...) but an error occured on my old mobile Samsung C3050. The media I wanted to download was just an audio mp3 file that I usually download easily.</p>
  
  <p>The error appears to be "Unknown content type."
  So, as my only HTTP header Content-Type was "application/force-download", I try to comment this and try again. Then, it works.
  But now, I am currently asking what this Content-Type means and if it can be mandatory for others mobile. I tested without the Content-Type on the iPhone 4 and it works, but I'm not sure of this compatibility for all mobile.</p>
  
  <p>Can someone explain me how that Content-Type works, why this isn't a standard MIME or everything else that can help me to be sure this is an optionnal Content-Type for every download, whatever the file, the browser or the device I am downloading on?</p>
  
  <p>Thanks everyone.</p>
  
  <p>Here is my PHP headers sent:</p>
  
  <pre class="lang-php prettyprint-override"><code>&lt;?php
  //Assume that $filename and $filePath are correclty set.
  header('Content-Description: File Transfer');
  header('Content-Disposition: attachment; filename="'.$filename.'"');
  // header('Content-Type: application/force-download'); Non-standard MIME-Type, incompatible with Samsung C3050 for example. Let it commented
  readfile($filePath);
  ?&gt;
  </code></pre>
  
  <p>EDIT : I just tried with a Sony Xperia, and the download wasn't successful: I only see the "html-encoded" bytes of my file I want to download.
  How can I know what content-type I have to use if application/octet-stream or application/force-download doesn't work?</p>