DEVICE FOR ELIMINATING INCOMING CALL DISPLAY TONE DURING BUSY STATE OF TELEPHONE FACSIMILE EQUIPMENT

PURPOSE:To prevent a chance of reception from being overlooked by forming the device with a circuit connecting a general telephone line to a line terminator integrated in a telephone facsimile equipment so as to always monitor an electric condition of an audible tone sent from a subscriber exchange and detecting a frequency component of a busy state incoming call display tone and with a circuit eliminating the busy state incoming call display tone interrupting to a channel. CONSTITUTION:A line input state is always monitored in the facsimile transmission and when a busy state incoming call display tone is interrupted to a channel, the frequency component of the signal is detected and the eliminating state is active. The busy state incoming call display tone is a 400Hz signal sent while being superimposed on a DC from the subscriber exchange and the detection circuit always monitors the channel in the facsimile transmission reception to confirm the input of the 400Hz signal and sends a command signal to a central processing unit. The elimination device is connected directly to the channel and eliminates only a prescribed frequency component under the control of the central processing unit.