Duplex communication
A duplex communication is a term used in telecommunication systems where signal can flow in both directions between connected parties. Duplex systems are employed in nearly all communications networks.
The term duplex is used when describing communication between two parties or devices. There are half-duplex systems and full-duplex systems. A half-duplex system provides for communication in both directions, but only one direction at a time. A full-duplex system allows communication in both directions, and unlike half-duplex, allows this to happen simultaneously.