In trader_4 writes:

[snip]
Your phone will work as long as there is power to the concentrator up
the street and all the others until it gets to the central office, as
long as they have power.
For all practical purposes there is no POTS anymore, powered by a big
battery in the central office. Even old style copper wired phones are
still slaves to line powered equipment along the way.

That may be true for some newer POTS, IDK. But it's not true for most
of the POTS out there, ie the installed base. When they went to what
amounts to concentrators
to enable the use of T1 lines back to the central office, that eqpt
was also backed up with batteries or UPS, etc. If you have service
over the old switched telephone system, then it's generally immune
from an AC power outage. That was and is it's one big advantage and
a major reason why people still keep it.

Yes, those batteries at the local "concentrator" (term used
a bit loosely and expansively) will keep your pseudo-POTS line
working during a power failure. For an hour or two or maybe five.

But that's it.

In the Good Old Daize, the Central Offices _all_ [a] worked
off floating batteries with generator backup. If the utility
power went out, the generators kickedin and typically had
a multi day, or longer, fuel supply.

[a] yeah, there's probably that exception somewhere.

I recall, back in the days of One Bell System, It worked [tm],
checking their daily telephone "newswire", voiced by Helen
Banks and Marion Marshall. Nice little puffery piece.

Anyway... there was one of those multi state heavy duty
ice storms which knocled out power for a _large_ area.

I remember her saying (number for illustration) that
of the hundred and twelve CO's in the blackout zone,
one hundred and eleven were operating ok on emergency
backup power...

(And the other would be fixed in a couple of hours).



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