A communications architecture that requires the establishment of a session between two nodes before transmission can begin. When the communications is completed, the session is ended (torn down). All circuit-switched networks are connection oriented because they require a dedicated channel for the duration of the session. The most ubiquitous circuit-switched network is the PSTN. In addition, packet-switched X.25, frame relay and ATM networks are also connection oriented, because they require receiving nodes to acknowledge their ability to support the transmission before data can be sent.