problem:: If you are in an important occasion(ex: business meeting), you don't want to allow unnecessary calls from unknown persons and also black list persons. And also you can not identify the importance of the call without look at the phone because you default use the same ringing tone for every contact.
My Solution:
My app identify white list/ black list certain contacts depending on your current location and also you can set the ringing tone depending on your current location and the person calling. And also you can set an individual message for different locations.
I think it will be very helpful to person who has busy schedule and person doesn't need to bother whether he missed the call of a special person or an emergency situation .