The legacy phone company virtually invented the U.P.S. (Uninterruptible Power Supply). To this day, their switching systems operate on -48VDC. That means all the computers, relays, backup systems and whatever else is required to produce dialtone and switch calls. The only thing NOT running off battery power is the HVAC for the building that houses the switch.
And it’s technically NOT a U.P.S. which, by design, SWITCHES to battery backup in the event of a “shore power” outage. The telco system runs 24/7 on a HUGE battery that is continuously recharged by rectified grid power. This is how, with more than a few exceptions these days, when the lights go out you can still place and receive calls on an old-fashioned telephone set that requires only a telco connection - no external power supply required.
Each cell of the huge battery I mention is about the dimensions of a 20-25-gallon cylinder. Each cell is of the flooded, lead acid type. Depending on the size of the Central Office and its switching equipment, the battery room can be VERY large, housing hundreds of such cells.
Before the deployment of the pair gain system, every line consisted of a pair of copper wires with one end inside the C.O. and the other inside the customer’s telephone. It was common that this pair of conductors extended many miles out into the rural. Picture in your mind a common two-wire extension cord laying on top of the ground from downtown to the farm house furthest away from the C.0. 10, 15, 20 miles is (still is) common and even longer lengths exist in certain, particularly remote locations. As you can imagine, building such infrastructure was no small task nor is its maintenance. (Call before you dig.)
The scheduled, or at least announced with some advance notice, outages in California and our having acquired so much equipment that REQUIRES A.C. power, the need for individual power generation grows greater every day. Some years ago, I purchased a Honda EU2000i portable, gasoline-powered generator. I paid dearly for it but proved that you get what you pay for. It is ultra-quiet. Two people can stand directly over it - under FULL load - and hold a “normal” conversation. It is an “inverter” generator. That is, it generates D.C. power that is rectified to PURE sine wave A.C. power suitable for powering sensitive electronics. Because of this technology, the engine can throttle down, drastically reducing already minimal operating noise, until the load demands - then it revs up. This thing would run ALL your electronic equipment at the same time including a HUGE flat screen and whatever computer and personal devices you may wish to charge. This particular model is “portable” (note quotes) and, with a little judicious extension cord jockeying, can run a large refrigerator (by itself) to get it back down to nominal coolness and, by itself, even a gas furnace. We spend more on far less utilitarian things so this should be completely “do-able” to anyone wishing to stay up-and-running in the event of a grid outage.
Many (most?) of us are well informed in the care and feeding of wind power and photovoltaic systems (solar). That’s fine and good information. We should become equally informed in what’s available in the field of consumer, “high” capacity, standby power provided by the fossil-fueled engine. That technology has advanced right along with “alternative” power.
Reliability: Given that all service providers have ready standby power, whichever service you choose should be “equally” reliable, even in a power outage. The reliability of each will be tested during the next community-wide - or larger - disaster. It is the post-disaster evaluation(s) that will determine the most reliable under those conditions.
They have standby power. You should, too. IF you do, even when the lights go out, you’ll still have cable, internet and landline phone. With a generator, the fun never has to stop. 