| 摘要 |
PURPOSE:To hold a conference using telephone sets easily by providing a main- wire calling circuit for main-wire terminating calling, by providing a call cross point for connecting ringing-tone transmission lines of three couples of lines to the main- wire calling circuit, etc., and by making a CPU control each circuit. CONSTITUTION:Three couples of lines are provided with independent talk-voice transmission lines 42, 52 and 62, and ringing-tone transmission lines 46, 56 and 66, and a terminal circuit is also provided as an interface to three couples of lines. Besides CPU19 controlling each circuit, this telephone set is equipped with a main- wire calling circuit for main-wire terminating calling, an extension calling circuit for extension calling, clock circuit 16 for lighting a lamp, and calling cross points for connecting ringing-tone transmission lines of three couples of lines to main-wire calling circuit 17, extension calling circuit 18 and clock circuit 16 via the terminal circuit. Consequently, the transmission rate of a control signal between the key telephone set and main unit 1 can be determined by the circuit composed of wired logic, so that a conference using telephone sets can be held easily. |
