Abstract

A half-duplex digitally-controlled telephone communication apparatus for permitting half-duplex communication between local and remote subscribers. Analog speech of one subscriber to be transmitted to the other subscriber is converted to a digital format, processed by real-time speech processing apparatus, stored in a delay buffer, and processed in modem apparatus for transmission to the other subscriber. In accordance with the present invention, the delay buffer provides a delay of a sufficient duration to compensate for inherent delays in the system in detecting the presence (or absence) of speech signals and serves to prevent the loss to the remote subscriber of portions of speech of the local subscriber, especially the onset of speech or rapid utterances of the local subscriber. The apparatus of the invention further includes apparatus for preventing the transfer of the communication channel or line from the local subscriber to the remote subscriber during normal pauses in the speech of the local subscriber.