Apparatus and method of recognizing establishment of speech channels in

Abstract

An apparatus for recognizing an establishment of speech channel in communication appliances connected in parallel to a common telephone line includes a hook switching unit for establishing a speech channel between the telephone line and a selected one of the communication appliances in accordance with a switch-on control signal, and for cutting off the established speech channel in accordance with a switch-off control signal; a detecting unit, connected to the telephone line and adapted to detect a loop current from the telephone line; a storage unit for storing a value of the loop current detected from the detecting unit as a one-channel value when the speech channel is initially established between the telephone line and the selected one of the communication appliances, and a control unit for generating the switch-on control signal to the hook switching unit in response to an incoming call, and for generating the switch-off control signal to the hook switching unit for switching a call conversation to another communication appliance connected in parallel to the telephone line when the value of the loop current output from the detecting unit is lower than the one-channel value while the selected one of the communication appliances is playing back a recorded message to the telephone line in an automatic telephone answering mode.