Blue Tooth Software

We are a USA based market research company. Currently we want to do some work in retail department stores like Macys and need some help with developing a blue tooth marketing software that can send out a bluetooth message to user cellphones ONLY : (A) If they are in the exit area of a department store (most department stores have several entry/exit points. We don't want people to get our message when they have just entered the store. Instead, we want them to get our message when they are leaving the exit area). OR (B) If they have been inside the store for 30 mins (again, we do not want people to get our message the minute they enter the store. This will disrupt their shopping experience. Instead, we want them to get our message once they have been in the store for 30 mins) Please advise if your can do either (A) OR (B) OR BOTH…....what is the cost and by when can you deliver. Key requirements: You should have a high level understanding of how blue tooth devices work to be able to do this. Best, Nitin