How can you receive an active phone line through broadband?
The best thing to do is to set up a wireless router at your downstairs point and then access the Internet anywhere in the house from that. Presuming you have a laptop that has wireless access. Then you don't need to worry about the line going upstairs. Your PC at the point of access can still access the net direct via the line, so it doesn't need to have wireless. So just get yourself a wireless router.