PURPOSE: To improve the communication efficiency by tapping the response signal, which is loop-backed and sent to a first mobile station with a base station by a second mobile station.

CONSTITUTION: When a dynamic registering signal A is sent to a base station 100 from a mobile station 200, the base station 100 sends a response signal B including an individual number and a dynamic code to the mobile station 200. The mobile station 200 receives this signal B to display the movement on a display device 209, and the completion of the dynamic registration is confirmed. The base station 100 sends the signal B to a mobile station 300 as a dynamic signal C simultaneously with the sending of the signal B to the mobile station 200. The mobile station 300 receives this signal C by a terminal equipment on a vehicle to automatically display it on a display device, and dynamic registration contents of another mobile station are confirmed. Thus, it is unnecessary to confirm dynamic registration contents of another mobile station by voice communication between the base station 100 and the mobile station 300, and the communication efficiency is improved.