If there are only two phone service providers for an entire large city and people have to choose from among those two, this is an example of an oligopoly.
Origin of oligopoly
- oligo– (mono)poly
From American Heritage Dictionary of the English Language, 5th Edition
- Derived, by analogy with monopoly, from Ancient Greek á½€Î»Î¯Î³Î¿Î¹ (oligoi, “few") + Ï€Ï‰Î»ÎÏ‰ (pÅleÅ, “to sell"). From oligo- +"Ž -poly