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.