Junctor
Encyclopedia
A junctor is a circuit used in analog telephone exchanges, including the Number One Crossbar Switching System
, Number Five Crossbar Switching System
, Panel switch
, 1ESS switch
and other switches.
In early electromechanical switches including Panel switch
, a "District Junctor" handled supervision and talk battery duties for outgoing calls, similar to the duties of the cord circuit
of manual exhanges. 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, of which the latter supplied all talk battery and supervision.
Stored-program analog switches such as the 1ESS switch
, had both simple wire junctors and circuit junctors. 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. Wire junctors were two-wire connections between trunk nets and other trunk nets or line nets. When three-way calling was introduced, three-port conference trunks were used, which only appeared on trunk nets. 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.
Number One Crossbar Switching System
The Number One Crossbar Switching System, or 1XB switch, was the primary urban local telephone exchange design used by the Bell System in the mid-20th century. Its switch fabric topology was based on the earlier urban panel switch system, which, in turn, was based on the turn of the century...
, Number Five Crossbar Switching System
Number Five Crossbar Switching System
The Number Five Crossbar Switching System or 5XB switch, designed by Bell Labs and made by Western Electric, was in use in Bell System telephone exchanges from 1948 to the 1980s...
, Panel switch
Panel switch
The panel switching system was an early type of automatic telephone exchange, first put into urban service by the Bell System in the 1920s and removed during the 1970s...
, 1ESS switch
1ESS switch
The Number One Electronic Switching System, the first large-scale Stored Program Control telephone exchange or Electronic Switching System in the Bell System, was introduced in Succasunna, New Jersey, in May 1965. The switching fabric was composed of reed matrixes controlled by wire spring relays...
and other switches.
In early electromechanical switches including Panel switch
Panel switch
The panel switching system was an early type of automatic telephone exchange, first put into urban service by the Bell System in the 1920s and removed during the 1970s...
, a "District Junctor" handled supervision and talk battery duties for outgoing calls, similar to the duties of the cord circuit
Cord circuit
In telecommunication, a cord circuit is a switchboard circuit in which a plug-terminated cord is used to establish connections manually between user lines or between trunks and user lines. A number of cord circuits are furnished as part of the switchboard position equipment. The cords may be...
of manual exhanges. 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, of which the latter supplied all talk battery and supervision.
Stored-program analog switches such as the 1ESS switch
1ESS switch
The Number One Electronic Switching System, the first large-scale Stored Program Control telephone exchange or Electronic Switching System in the Bell System, was introduced in Succasunna, New Jersey, in May 1965. The switching fabric was composed of reed matrixes controlled by wire spring relays...
, had both simple wire junctors and circuit junctors. 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. Wire junctors were two-wire connections between trunk nets and other trunk nets or line nets. When three-way calling was introduced, three-port conference trunks were used, which only appeared on trunk nets. 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.