Abstract: A route selection service control system for selecting an optimum one of routes connecting an originating-side terminal to each of terminals owned by an identical subscriber and connected to respective communication networks operated by different telecommunication carriers. On receiving the identification number of a terminating-side subscriber, a reading unit refers to terminal type storing unit and reads out the terminal types and terminal numbers of a plurality of terminating-side terminals associated with the identification number. A position information acquiring unit acquires the current positions of the terminating-side terminals. A distance calculating unit calculates the distance between the position of an originating-side terminal and the current position of each of the terminating-side terminals.