PURPOSE: To improve the reliability between a subscriber terminal equipment and a subscriber exchange by securing the channel between the subscriber terminal equipment and the subscriber exchange accommodating the subscriber terminal equipment automatically by means of other path in a data exchange network even when the subscriber exchange is out of order.

CONSTITUTION: A subscriber terminal equipment 11 is directly accommodated in a radio station equipment 10, and radio station equipments 12, 16 are connected to subscriber exchanges 12, 16. Two subscriber exchanges or over to which the radio station equipment is connected are provided to the system. A monitor controller 123 of the radio station equipment 12 connecting to the subscriber exchange 13 recognizes the operating state of the subscriber exchange 13 to be connected, and the radio station equipments 12, 16 connecting to the subscriber exchanges allow controller 124, 164 respectively to compete the connection right to the subscriber exchange based on the operating state. Thus, the channel to the radio station equipment 10 to which the subscriber terminal equipment 11 is accommodated is selected automatically depending on the state of the subscriber exchanges 13, 15.