I read about that... interesting!!
My last Host at this casino used to say... text me the machine number when you are on a machine. But, twice on different visits he called our room after we had left the floor.. so he knew that we were in the room.. I know that it can be tracked when you use a room key.
My new Host called me a couple of months ago on my cell and said "where are you? We were in our room....she was surprised and said she couldn't find us..... weird...