In other words, in the old days, phones did not have a jack in the wall - AT&T came to your house and wired their network directly into your telephone. They did not want the RJ-45 jack which made consumer Modems possible. The government forced them to open up their network to other device makers, to competitors.
https://en.wikipedia.org/wiki/Carterfone
I really wonder if the modern techno giants would be able to be regulated by the government if they became stagnant monopolies.