This paper examines the price response of wireless carriers to the introduction of number portability in the U.S. I find that wireless prices decreased in response to number portability, but not uniformly across plans. Average prices for the plans with the fewest minutes decreased by only $0.19/month (0.97%), but average prices for medium and high-volume plans decreased by $3.64/month (4.84%) and $10.29/month (6.81%), respectively. The results suggest that higher-volume users in the wireless market benefited more from the policy-induced reduction in switching costs.