Prison Communication Monopoly

The New York Times reports that prices for cell phones, emails and wire money transfers are "sky-high" and the reason is a lack of competition.  In fact in some cases, the private firms that are providing these services are the prisoner's only options, meaning for that list of customers, they are monopolist's, and as I demonstrate in Prin. of Microeconomics, firms that are monopolists have a profit maximizing incentive to charge higher prices than firms in more competitive markets.