Abstract: A least cost call routing system operates in conjunction with one or more telephones disposed in a location to provide least cost telephone call routing using a selected one of a number of commercial telephone carriers. A central server stores a plurality of telecommunications carriers and associated billing rates. A user's computer registers with the central server by providing certain user identification information. The central server generates a customized database of telecommunications carriers and associated billing rates for the user in response to the location of the user. The customized database is stored on the user's PC for use in routing telephone calls along a least cost route. The central server establishes an account for the user at each of the telecommunications carriers in the user's database. The user's PC periodically contacts the central server to receive updates to the customized database.