In early electromechanical switches, a "district junctor" handled supervision and talk battery duties for outgoing calls,[1] similar to the duties of the cord circuit of manual exchanges.
The junctors for incoming calls were simple three-wire connections between the incoming frame and the line frame.
In the later electromechanical 5XB switch, junctors only consisted of three wires to connect the two legs of a call: the line and the trunk,[2] of which the latter supplied all talk battery and supervision.
Circuit junctors were in the form of plug-in circuit boards to provide talk battery and supervision for intraoffice calls and were closely similar to intraoffice trunk packs, with two scan points and two signal distributor points per circuit, two circuits per plug-in pack.
All junctors appeared in subgroups of sixteen on plugs or jacks at the Junctor Grouping Frame, where as many subgroups as required were plugged into other trunk nets, line nets, or circuit junctor frames.