I see what you were getting at now and you’re right about the load from those cell towers. Most are going to still be active, at least for a little while, and there’s a good chance that a heavy cell usage spike would crash the system. There’s a reason most of us Bell guys have land lines in addition to our cells and it has nothing to do with company loyalty. ;)
My dad put in 45 years with Ma Bell. I've been in the old mechanical switching offices when a major calamity hit and I've seen the power rooms also :>} Ma Bell can run their C.O.'s for weeks. Their power plants were designed to handle the older mechanical systems which was a far greater load.
But you also got to consider outside the main building digital capabilities would be lost including S.L.I.C.K. capabilities. That would somewhat limit available lines per area the SLICK serves.
I use cordless phones but the base is on my computer APU. You could not pay me too have Cable TV phone service. LOL. I even have a couple trusty old Western Electric phones near by if all else fails.
Right now i have two land lines one for me one for puter and 4 cells in my name for family members. The cells are my back up phones if the land line fails and vice versa. When the SLICK dies in my area {at least twice a year now} it's cell phones for a day or so.
If I'm out and see a wreck I don't even attempt to call 911 anymore. So many persons have cells the chances are within a minute of a wreck on an interstate 50 or more persons will call 911 for that one wreck. Pappy used to service 911 also after he went back outside. I was his unofical co-worker on late night call outs to bad parts of town. He mainly worked on data circuits.