How to implement a directory?

Question

MySQL

How to set up links and queries for the directory? Now there are 5 tables. Branches, floor, telephones, linking table of floors and branches, telephones and branches. I bring out all the departments, by pressing the floors are displayed. Now the question is how to break people down by floors, so that I would press the office, then the floor and display contacts only from this floor?
Phones

Departments

Floors

Communication between floors and departments

Communication between phones and departments