The trunk unit (1) is installed on the left-hand side of the switchboard directly above the magneto supervisory lamps. The trunk unit is divided into eight segments; each segment corresponds to one of the eight telephone channels running between the switchboard facility and the automatic central office. The channel jack in each segment provides the operator with access to the corresponding channel. In addition, each segment has two indicator lamps and a button. The indicator lamps enable the operator to monitor the status of the channel. The button provides control of the central office line and permits the switchboard operator to break the connection when a call is completed.
DesignationTM 11-5805-553-13
EditionMar 1984
StatusSuperseded
Pages148
FunctionComms Signal
CollectionRecent Archive
Public domain (U.S. Government work)