I own a landline, much to my providers dismay, as they have to maintain the line then. Laws about landline phones are OLD, and hold the providers accountable, mostly to do with emergency services liability etc. You can report the provider to the Feds if you really want to. If it goes down, they send someone within a few hours to troubleshoot it. meanwhile, they offer my internet also. If that goes down, the laws are lax and they will ignore it for days at a time.... unless I call right away and tell them I am tracking the downtime because legally I do not have to pay for the missing service.
Last I checked, when cell coverage goes out the consumer is supposed to deal with it, maybe the provider will throw you a bone. might be able to call up and complain and not pay for the downtime, i am not sure. But I know they are under no obligation to fix it like a land line other than people will find a new provider(free market at work)
Landlines work during a power outage also, and you don't have to charge them lol. Hardlines are not obsolete, they are just more expensive and regulated for accountability for the providers. Maintinaing miles of line is more expensive than a single tower.