BTW. For short outage batteries in terminal is enough, and BTSes have UPS that last quite long. Basically when my neighborhood has power outage (once a year maybe) for max 2-4 hours, cell service still works (a bit slower because everyone switched to it).
I regularly get power outages of several hours in the pacific northwest [1]. My local cell towers go about 2-4 hours before dropping off. The telco DSL drops immediately, not sure about the cable company. Gotta make sure you've got offline entertainment or you're gonna be real bored.
[1] mostly from trees falling into lines; the same soil conditions that make undergrounding lines very expensive also contribute to trees having shallow roots, saturated soil and high winds strongly implies no power. Also, local regulation requires the power company to pass costs of most undergrounding along to the affected customers and they have to approve the work; most people don't want to spend their money on undergrounding, so it's not typically done.
Natural disasters. In the early 90s a blizzard knocked out power on the US eastern seaboard for weeks in some areas. Two years ago Texas's grid was compromised for nearly a week during the ice storm, and even cell service was down.
I'm sure there are other examples. How long was power out in New Orleans after Katrina? Puerto Rico after Maria?
When superstorm Sandy hit New York in 2012 I lost power for 2 weeks. Local stores/gas stations/restaurants were without power for about a week. This was in a densely populated suburb, not a backwater.
BTW. For short outage batteries in terminal is enough, and BTSes have UPS that last quite long. Basically when my neighborhood has power outage (once a year maybe) for max 2-4 hours, cell service still works (a bit slower because everyone switched to it).