A dealer-locator service is provided to mobile telephones (40) in a mobile telecommunications system (FIG. 1). When a mobile telephone initiates a call to the dealer-locator service, a mobile telephone switching office (MTSO 41) identifies the one of a plurality of base stations (20-23) through which the call is made. A dealer-locator service apparatus (43-45) then uses this base-station identification, rather than the telephone number of the calling mobile telephone, to look up in a dealer-locator database (300-301) the one of a plurality of business locations (30-33, 50-52) of the dealer that is in the vicinity of the identified base station, and hence in the vicinity of the calling mobile telephone. The apparatus then reports the address of the one business location to the caller, and optionally also causes the MTSO to connect the call to a telephone number of the one business location. The dealer-locator database may be programmed by individually calling the dealer-locator service from each dealer business location via a mobile telephone that is positioned at that dealer business location and supplying that location's address and phone number. The apparatus records the identity of the base station through which the call was made along with the supplied information in the database.