title: how to ask for more permission after initial authentication in Facebook
body: <p>I've a facebook app at which I've asked users to give their email, work Info etc. The users have already granted the permission to retrieve these information.</p>
  
  <p>Now I want to retrieve their phone numbers also but I've not asked for it previously.</p>
  
  <p>So how do I ask the already authenticated users to give access to their phone numbers?? Is their some code which I can add and next time they logged in, they are prompted to authenticate that extra info??</p>