NETWORK CONTROLLER

PURPOSE:To eliminate the need for the manual switching of telephone circuits and to enable the use of a telphone set attached to a device, by connecting a telephone circuit with preference to the telephone set when an off-hook of the telephone is detected by the 1st and 2nd off-hook detectors. CONSTITUTION:When a telephone set 200 is hooked off while a data terminal device 300 is under communication, the output signal F of an off-hook detector 110 changes to 1 from 0 to start a monostable multivibrtor 160. The output signal G of the monostable multivibrator 160 keeps a O state and is reset to 1. An automtic dialing part 140 detects the off-hook of the telephone 200 from the change of the signal G and informs it to the device 300 to discontinue the data communication. While a switchboard detects a call with a flow of a loop current via a telephone and accepts the dial pulse supplied from the telephone 200. The output signal H sent from an off-hook detector 120 is always set at 0 while the telephone 200 is busy. Thus the data communication carried out by the device 300 is inhibited.