DATA COMMUNICATION SYSTEM

摘要

A controller (A) provided at the upper layer of a predetermined telephone circuit (L) and adapted for monitoring pre-speech notification information and controlling connection between a telephone set (T) and an exchange (2) is connected to a telephone network (1) having a pre-speech information notifying function. A data transmitting/receiving terminal (TA) is connected to the controller (A) parallel to the telephone set (T). When the controller (A) judges that pre-speech notification information is not specific pre-speech notification information, the controller (A) connects itself to the telephone circuit (L); when the controller (A) judges that it is, the controller (A) connects the data transmitting/receiving terminal (TA) to a transmission data transmitting/receiving terminal (TA) so as to allow them to transmit/receive data between them.