When I started doing inspections (audits) of facilities of pharmaceutical suppliers, I'd visit a lot of data centers. There were hidden away in plain site. Usually the basement of a building or what appeared the basement but was actually a cave underground. I'd go and visit the server used for my company and call it good. I'd mostly go because there data centers were such cool places to visit. There were about half the size of a football field. Nothing huge but still, that's a lot of computers in one place. Later, companies moved away from dedicated data centers and moved to AWS and the like and we didn't know where the data was stored. They had primaries servers with secondaries running full time. Plus tertiary backups. I don't know what they use now. It was a challenge for the pharmaceutical industry to not know the exact server where our data was stored. We've eventually gotten comfortable with it along with FDA.
I know a lot of cell phone towers used to have an analog fiber link back to the phone companies, then phone companies would route calls and data to each other. Lately a lot of them were just analog to digital converters on the tower and their digitized signals are sent directly to a data center, connecting to a card on a server, that routes the call and data to each other over the internet. They would also spin up and down data center and route those "calls" in and out of certain computers based on time and load. Your phone company is just a "virtual" computer inside a data center, or sit on the same server hosting BITOG and never left that one computer.