here in the boonies, every cellular carrier, every internet provider, every--everything... goes out with single fiber cut. even cable tv goes dark since they took out local headend here (connected now via fiber to a town an hour away).
except for POTS, and the voice and data carried on it. when the whole town gets cut-off from the outside world for a whole day or more, which has happened four times in the last four years. the good ol' shitty telco is still going; their cables are separate, and go entirely different directions out of town.
that's why we still have a landline at the office; having a line-powered phone for when the power goes out (also not uncommon) is just a bonus.
system disk encryption is possible, yes.