I have 2 phones plugged in that work fine with no power, including the one on my night stand, I also have another one in a drawer I can use if needed.
The batteries at the CO will last longer than my UPS
The generator at the CO will last longer than my generator
The power company will put a higher priority on restoring power to the CO than they will to my house or my ISP for that matter.
As I mentioned previously, the ability to have a more reliable access to 911 is not the only reason we have a land line. We use it for our local calls which don't cost us anything extra.
It's simply ridiculous to claim that a land line is no more reliable than VoIP, in the last 2 major earthquakes we have seen (94 and 71) power was out for more than a day but the land line never stopped working, after the initial flood of calls following the quakes the phones worked fine for contacting & communicating with friends & family.
If I switched to a VoIP provider I could save a few bucks but I've introduced several more potential points of failure into the scenario, even if I have a spare DSL modem and router (which I do) they won't run more than a few hours on a consumer-grade UPS, I suppose I could buy a $1000 higher end UPS to run me for longer but that's going to create it's own problems and increase my power costs.