I have no idea how they are doing it but my brother is in Rockport, TX where Harvey made landfall and he has cell service, I talked to him the day after Harvey went through.
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Actually, the cellular system is designed to self-heal at the trunk level. Most sites have power generators.
That is something I noticed way back in ‘83 when we were doing boundary surveys for the remote repeaters. Every company operating on those sites had generators and big fuel tanks.
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telecom companies now have disaster units they can deploy to relay the signal after a tower goes down. They basically just run in and turn on the generators and send a signal if it’s safe to do so.
One thing bad about quakes, generally there is no warning whatsoever.
It's why I like radio, no need to rely on anyone, it never seems to fail.☺ In major events, not everyone are going to have utility workers show up and fix the problem in 8 hours. To get reliability it should involve solar panels and storage batteries to power several radios. Good 100 watt panel are down to about 120 bucks or so. Off the grid, very independent. Pretty cheap way to have reliable communications for many years in the event of a large scale event or even a wide scale grid failure etc. Some people won't go to the trouble, and that's ok. I just like being independent.