(1) In telephony, circuits that connect two switching systems, as opposed to connecting a customer line to a switching system.
(2) In the CVS team development environment, the main stream of development, also referred to as the HEAD stream.
(3) A telephone connection between two central offices or switching devices. In DirectTalk, a trunk refers to 24 or 30 channels carried on the same T1 or E1 digital interface. See also channel.