No dial tone. -47 volts

I'm an at&t technician so trust me on this. You most likely have what is known as a "dirty open" on your cable pair in the outside telephone plant or inside your location. When you look at the pair entering your location, or wherever you happen to be testing from you see about -48 to -52 vdc across the pair. You'll have no dial tone or loop current. This is because one or both wires in the pair is making enough contact for the voltage to get across but not enough current for the dial tone. One or both wires are ever so slightly broken apart inside the wire insulation. This is all assuming you're looking across the pair from tip to ring. If you see -47 vdc from the ring to ground but not across the pair, from tip to ring, then your tip side, the grounded side, is likely open somewhere. A telephone technician has the proper test equipment to identify this common problem and can measure distance to the open location and therefore repair it.