That small gray box on the side of your house (the one that's not a
fuse box or a
gas meter) is called a network
interface which is where the
phone company's responsibility ends and yours begins.
Even if you're not a real geek, go make friends with this box. You should be able to jack in at the box and test your lines. It's where the free service call ends and the $45 service call begins.
It's the little friend of the large green box on the street corner.