PUSH TO TALK

Push To Talk refers mostly to a transmission system that carries only one voice channel - and that voice channel is used for both transmit and receive.  Two people on such a system cannot talk and listen at the same time - since there is only one channel connection.  Each user in turn presses a button to "push to talk" and then transmits to the other.  These systems, such as Nextel DC, often are able to tell if the other party is transmitting, and may not let the second person push to talk and transmit till the first party is done transmitting.  Of course, in such systems, it is best to keep each persons portion of the conversation short since the second person would be unable to talk or add to the conversation until their transmission is done and it is the other partys turn.

Push to talk has also been used in some communications systems, such as early MTS car telephone that had two channels.  This early telephone system was manual, and pressing a push to talk button on the telephone handset would transmit and that would alert an operator that a car telephone user wished to place a call.