I read the previous question about lines dead, and it just didn't quite apply to my situation. All of my lines are dead, yet the jack in the box outside is functioning. The phone company says it's my problem not theirs, but I can't figure out why all four lines coming out of the box should be dead, if the problem isn't in the box.

If it makes it to their Box, A good line should have about 48 volts(on hook), be sure jumper is plugged in outside to restore connection inside. Call your house from another location, if it rings and rings, line is open, if it rings busy, then shorted(loaded down).
A good pair should connect to red and green on phone jack.