On Wednesday, January 16, 2019 at 12:42:43 PM UTC-5, danny burstein wrote:
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.


I agree, it depends on the size of the batteries. But the telcos were
not shy about having large batteries either, the installed base has been
deployed for 40 years when reliability was a primary concern,
so I'd suspect it's more
at the longer end of your time range or beyond. If it wasn't there
would be a lot of people complaining for decades about losing phone
service during power outages. I've lived in quite a few different
places and never recall losing phone service on the switched phone
system during any power outages.

I agree that it's not long duration, like having a generator at the
central office. But it's also not like you lose your POTS phone during
the typical power outage that lasts a few hours either. Fretwell has
a valid point, that even copper for many people probably won't last
a long time if they are not direct into a CO. And unless you have experience
with power outages of varying lengths, you really don't know how long
it will last. I got rid of my copper, VOIP and cell works for me.