Not so Scary!
The issues you raise should not be that scary and I would like to offer some rebuttal opinions.
VoIP service providers do not require that you have a computer running to obtain service. In fact you do not even have to have a computer to participate although paying for broadband service without a computer, just to get VoIP would cost much more than PSTN service by itself.
The need for power could be considered an issue, however a generator or ?killer UPS? is not required. At best, VoIP adapters and associated broadband router and modem require very little power and can be easily maintained with a UPS costing less than $100.00. In my case I have three Linksys devices that use between 5 and 12 volts and 0.5 to 2.0 amps each and consume = 5 watts of power per device.
I would also wonder how many telephones in use are actually wired handsets? It would not surprise me if the majority were wireless handsets and therefore also subject to power failures.
Sure any networking solution except satellite, microwave, cell service etc. requires a wire line connection. but wether that is cable or DSL the service provider powers or lights the media.
