title: Download file in browser from CDN and set downloaded file name
body: <p>I've got call recordings stored on a CDN (Rackspace CloudFiles) with names like:</p>
  
  <blockquote>
    <p>KPOWIEJFIE2034020SVN10ASKZALBMRI.mp3</p>
  </blockquote>
  
  <p>(They're Twilio Call SIDs).</p>
  
  <p>My application (CakePHP) displays a list of these recordings, and uses an <code>&lt;audio&gt;</code> tag to allow them to be played on the page right from the CDN. I need to add the option to download the file directly as well, but I want to download the file named something more like this:</p>
  
  <blockquote>
    <p>Call from Alex to Firm, Inc, 8/19/2011 4:00pm.mp3</p>
  </blockquote>
  
  <p>I know how to do this with PHP and readfile() to set the name to whatever I'd like, but that requires the file data be streamed through my VPS. Besides being billed twice for the bandwidth (once through the CDN and once through my VPS), this would defeat the purpose of having my files on a CDN (speed and availability). I have the files named only with the call SID on the CDN for security.</p>
  
  <p>Can I do this with browser-side somehow? Can JavaScript change the name of a downloaded file on the fly?</p>
  
  <p>I appreciate any help!</p>