We estimate a two-step control-function model that relates incumbent prices for small-business telecommunications services to the number of facilities-based entrants, cost, demand, regulatory conditions, and a correction for endogenous market structure. Results show that the price effects from entry are understated in ordinary least squares regressions. When controlling for endogeneity, prices are negatively related to the number of entrants, indicating that markets without a competitive presence could exhibit market power. These findings should prove helpful to the Federal Communications Commission and other State regulators determining the conditions under which price and other forms of regulation may be relaxed.