Indoor Fencing/Location - FAQ

Hi Team, I have successfully fenced a meeting room. My aim is to notify /update the web service if someone is occupied/there in the fenced meeting room. I have few question achieving this. Once the room is fenced, do i need to keep the same set of beacons always there in that room or is it enough to keep only one beacon ? How to notify if a person enters into and comes out of that meeting room ?