- This scenario might be triggered by two different situations:
   A) Another Loop user is calling me via a Loop client
   B) Another user (either logged in Loop or not) clicks on a URL Callback

- When an incoming call is received I am notified through an attention screen so I can be notified when the screen is switched off, Loop app is not being executed or in background. 

- The attention screen shows me the Identity of the caller (if available) and if a contact in the address book contains that identity it should also show the contact name and picture (UX Details needed). 

- The attention screen also shows me the options to reject the call or accept it. In case the call is rejected, the other party is notified about the rejection and I go back to the app I was using before the attention screen popped up. In this case a new call log entry of type missed will be added. This will be also be the case if I don't answer the call during the configured answering time.

- In case I accept the call, As a FFOS Loop application user, I can answer an incoming call with audio only or audio + video, so that I can decide if the caller will see me or not and the call-in-progress screen is shown (see US in bug 1010324)

- The clicked URL used to originate the incoming call will be revoked after a guard interval by the server so that no one will be able to call me through that URL anymore (This only happens if this scenario is triggered by option B as described above)