"R J Carpenter" writes:

When the lights go out, the
phone fiber-to-copper electronics run on battery UNTIL THE BATTERY RUNS
DOWN, a matter of a couple of days. So your phone will fail during an
extended electrical outage.

Unless you simply put a twisted copper pair in with the fiber cable used
in FTTH (which for practicality of installation and maintenance is
certainly going to be a small "cable" of some sort, not just a single
fiber).

Undersea fiber optic cables -- which are a different matter, of course,
but aren't physically that much bigger than the coaxial cables used for
cable TV -- carry DC electrical power at _4000 V_ all the way across
oceans.