And I ask, what's the difference? Let's try not to be pedantic here, because if they are a legal monopoly, at the end of the day they have to do what the government says, because if they don't the government could just tear the monopoly down and prop up competitors.
Nationalized companies are owned by the state. AT&T had/has private shareholders.
2) Control
With ownership comes control. The U.S. government granted AT&T a conditional monopoly. In the early 20th century it was in exchange for extending service across the nation. Mid-20th century for defense work.
Aside from these conditions the U.S. government did not exert control on AT&T's operations.
>Nationalized companies are owned by the state. AT&T had/has private shareholders.
I feel like this is being pedantic. While there are shareholders, taxpayers have funded the infrastructure and are paying for it in the form of tax breaks.