> You put the battery in the RC and have a battery maintenance schedule. They do that today: the CO battery is just for phones within a few miles of the CO, so rural setups use distributed batteries.

I don't know for sure about POTS, because the pricing was prohibitive, but my local telco certainly did not use batteries at the remote terminal to keep ADSL online... when utility power dropped, ADSL dropped instantly, even when the outages were under 10 seconds.

My local wireless telcos provide about 4-8 hours of wireless after utility power drops. Not great, but better than what I got from ADSL + voip.

My neighborhood (along with most of the city) was without power for a couple of weeks following the 2012 derecho. I had VDSL at that time.

The VRADs scattered around the city included a battery that worked for as long as it worked. But I never did discover how long those batteries would last, because AT&T brought portable generators out to supply power to their VRADs.

I kept my end alive with the portable generator that I was using intermittently for everything else along with the backup battery that the modem came with.

The VDSL circuit never dropped during those two weeks -- and yes, I read the logs afterward with some astonishment. :)

(Since the RF environment was extremely quiet, wifi had fantastic range. I opened up an SSID for anyone within earshot to use and some folks actually did use it.)

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Fast forward a dozen or so years. When the power dips in my neighborhood, the cable network drops out with it. So, sure: I've got a small UPS for my little stack of network gear, but fat lot of good that does when there's nobody for it to talk to.

And I've got ways to use LTE/5G as a backup, but the performance of the cell network also nosedives at that same time. It's not clear to me if that's due to a service interruption or instead due to everyone's pocket supercomputer switching from wifi to cellular data, but whatever the cause: It turns pretty useless.

(I'm on FTTH fiber now but it's only been a week. We'll see how it does the next time there's a power issue.)