While GPS offers high accuracy positioning, its application is constrained by indoors or under shaded space. As GSM BTS deployment is strictly and regularly allocated, it fits mapping coordinates for localization if signals can be properly received and identified. The proposed method formulates an algorithm to calculate the received signal strength (RSS) from vicinity base transceiver stations (BTSs). An intersecting area can be determined as the reference locations in positioning. To support this study, a BTS database should be offered from system provider. From several experiments, the performance and reliability of mobile positioning is improved from a previous work for faster solution and better result. With plenty BTS data, the positioning accuracy can be guaranteed. The proposed method is feasible and valuable for indoor applications.