What is a natural monopoly depends on government regulation. In particular regulations granting access from one company's system to another's can stop natural monopolies from being natural monopolies.

A simple example is that the pattern of long thin property rights needed to create a railway system completely blocks anyone from creating criss-crossing railroads that would allow them to compete. But government rules forcing the initial company to allow competitors to cross or share its railways will create competition.

Forced access to long distance telephone networks has the same effect.