When I worked at the Telco that serves all of Northern Canada - the telco that has the largest operating area of any telco in the world, in fact - we had an outage that took out everything for between 1 and 3 days.
When I say everything, I mean if you picked up your phone you didn't get a dial tone. Or cell phone. Or internet. Even people that still have 2-way radios to use as phones were out of luck.
There is no other provider for every single one of those customers, so not a single person had a single shred of connectivity.
In the larger cities they posted Police and EMT Personnel on street corners in case people needed 911.
That was a rather big outage, caused by a backup generator not starting during a power outage. We were still trying to bring systems back online a week later that had never been shutdown in 20+ years.