title: unique user on mobile site
body: <p>I am developing a django web site to be used with <em>mobile phones</em> (not just smartphones), only in public places that have wireless (malls, resteraunts, etc.).</p>
  
  <p>How can I follow unique users on my site? I want to mesure time spent, visit depth and so on BUT most of them will share the same IP.</p>
  
  <p><strong>EDIT:</strong> I will clearify myself: The site is to be used (without logging in) only in places with wireless. Smartphones will probably use the wireless, and non-smartphones will use their cellolar network. I'm looking for best practice to follow them uniqly regardless of the device/network.</p>