PURPOSE: To guarantee sure calling at a time zone crowded with much communication by providing a function receiving and cancelling the reservation of call from a subscriber terminal device to a data exchange station when the subscriber terminal device receives a specific signal during communication.

CONSTITUTION: When a terminal device 1 transmits a call reserving signal during data transmission/receiving between terminal devices 1 and 5, a receiving circuit 301 in a data exchange station 3 detects it, deletes it from the data expected to the terminal device 5 and also informs the detection to a receiving circuit 302 via an informing line 311 while adding the said call reservation signal to a terminal number of the terminal device 1. When the said transmission/ reception is finished, a cut-off detecting circuit 300 detects the cut-off of a call by the terminal device 1 and informs it to the receiving circuit 302. This receiving circuit 302 commands the inhibition of incoming call to a communication managing circuit 31 and also the start of timing to a timer 303, then the communication managing circuit 31 inhibits the incoming to the terminal device 1 and awaits the calling from this terminal. When the timer 303 reaches the specified time, the incoming inhibiting state to the terminal device 1 is released.