I was in Toronto, Canada when the power went down 6-7 years ago for 3 days or so. Few people had made preparations such as laying in candles, canned food, et.c. Fortunately the processed water supply is gravity fed from reservoirs located in the higher land north of the city.
Countries where the public electricity supply can be 'intermittent' are far better prepared. Even residences have small gasoline-powered generators, and cans of gas/petrol to refill the tanks. High-rises all have auto-switching generators, as do hotels and even restaurants.
The cellco networks are protected with small, auto-start, propane powered generators to charge the batteries, In the northern climbs, where the are some hills/mountains up to 3000 metres high, protection ensures continuous power for days on end.
Most all of the computers in my office are laptops, chosen mainly because of their 'power-fail' protection offered by batteries. All our LANs and WiFi units are similarly protected. Our lighting is by LED which are again low voltage.
In the States cellco's operated by telco's such as A T & T have no excuse as the telephone switching centres typically employ 'battery' technicians who spend all their time providing TLC to banks and banks of batteries to ensure their long life. The real reason the batteries are there is to ensure reliable communications.
Cellco's, from what I have observed, tend to be on the cheap side, maybe a bank of rechargeable batteries to provide a few hours power bridging, certainly nothing to ensure continuous operation for several days. The FCC is in a position to modify cell licences to ensure there are minimal power fail working conditions.
Given the profits cellco's make, it is not as if they can't afford the tax-deductible outlay, it's just they don't plan properly.
Now, in Canada, office space rental advertisements often trumpet that they have 'uninterruptable' power!