Stephen wrote:
> This is true as most people know but where does the phone company get
> its 50 volt dc come from. I suspect it is from an electricity company.

Batteries charged off of the grid, or off of generators started when the 
batteries get low if the electricity is off.

Ever see a room with hundreds of cubic feet of glass cases full of acid 
and lead? It's pretty cool.

You could run a normal-sized central office off batteries for several 
days, or several weeks if you start up the generators occasionally, 
without any outside services. If everyone with knowledge disappeared, 
the phone system would probably run three to four months before it broke 
down enough to have a major network partition.

(All this was from my days in the local telcos 15 years ago in the US, 
so it has probably changed since all the deregulation really had its 
effects.)

-- 
   Darren New / San Diego, CA, USA (PST)
     "That's pretty. Where's that?"
          "It's the Age of Channelwood."
     "We should go there on vacation some time."

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