Goes without saying that documentation on this plugin doesn't exist. If I'm missing something, please forward a link to documentation.
For Phone Mapping settings:
Username: <-- Is this the Openfire user or Asterisk user?
Device: <-- Is this the name of the phone device the user has, such as Linksys SPA942? or the UAD specified in Asterisk for the user? or whatever you want it to say?
Extension: <-- This is self explanatory.
Caller ID: <-- Custom Caller ID to be used when dialing from IM? Defaults to what? The Extension?
Primary: <-- What does this mean/do?