Prior to the widespread adoption of the Web, it used to be necessary to talk to a lot of people on telephones to accomplish the same sorts of tasks that we do on websites today. Ordering products. Requesting forms. Starting/changing/terminating services. If you want to do business with someone, either you have to have a brick-and-mortar office near them, or be able to take calls. And people had to field those calls.

That doesn’t mean that call centers don’t exist any more, but they’re a lot less important as a way to interact with a company.

Prior to telephones, it tended to require sending letters, and I’m sure that there were a ton of people who had to open, process, and write correspondence that telephones replaced (though in that case, I suspect that there was some overlap, though the skillset isn’t exactly the same; a good typewriter operator isn’t necessarily great on the telephone and visa versa).