Hi Jim,
I just came back from a tour of one of our local phone company’s central office (CO) and this is what I learned: Besides finding out how our phone lines work, I found out that the hardware there runs on 48 volt DC power. There is a large battery bank in the basement and the batteries are charged by the grid. It is made up of large clear cylinders and you can see the acid level and the plates inside. In the case of the grid going down it has a generator back up. Many of these offices are unmanned. I also found out that there are many small remote units around that run on a couple of deep cycle batteries for back up power around town. In the case of a prolonged power outage the technicians will cycle through the remote units with generators to charge up the batteries.
I was also surprised at all the circuit boards. An electromagnetic pulse (EMP) would easily take out [these microcircuit boards, and hence wipe out] all the phone circuits.
I know that society would have to totally break down in order to make use of these resources but I bet not too many people know about the battery banks. Just something to keep in the back of your mind because every town will have something like this. – Adam in Ohio