fibre optics go from the green cab near your house to the local headend (virgin media's local building that talks to your house and the main 3 headends in the country). from this green cab a twin cable is pulled either straight to your house and conected to your brown box (ETB). or in some areas the pull it from a pit (slot box) somewhere outside your house. it goes through a tee that is at the edge of your propertythen to the brown box on your wall. the twin cable (catv and telco are terminated thier) form the brown box it is taken into the home to where you rquire your telephone or STB...
hope this helps just ask if you need more info on certain points
or if you never understood what i wrote lol