Nobody has a legal monopoly. AT&T was broken up in '83, after legal action that went all the way back to '49. The government tolerates defacto utility monopoly only where there is a transparent, adversarial process for setting rates. But in the last 40 years, there has been a rolling deregulation experiment which tries to introduce limited competition to allow market based rates. It hasn't worked very well, in my opinion.

The tell of a true monopoly is the rate setting process. Market rates imply a relationship between supply and demand. In the case of telecom, the supply is essentially infinite, so rates are set for every reason under the sun. But the hoped for supply/demand effect isn't among them.