That I can help. Back in the day, to access someone’s else computer you literally hooked up yours to a phone line. Your desktop would then dial to some number you got that had another computer listening to answer, and they would start a “conversation”. Your computer sent what to us would sound like noise, the receiving computer would listen to that noise and answer back. Voilá, you’re connected to a network!

This is how it sounded like

And here’s an explanation about what’s happening.