US3740485A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Central office private branch exchange telephone system
Assignee: AT&T Inc
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Filing: 1971-11-24
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Granted: 1973-06-19
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Expires: 1991-11-24
Abstract
Abstract Private branch exchange service is provided by the switching network of a telephone central office. The PBX attendant is provided with a console which includes circuitry for completing calls to PBX subscriber stations through the use of dial transfer circuits in the central office. Loops for the PBX attendant console comprise lines of the central office which are associated with a PBX main station directory number and the PBX subscriber stations also employ lines of the central office. However, these stations can be reached only through the action of the PBX attendant''s console and the PBX stations do not have directory numbers of the telephone offices associated therewith.
Inventors
- 👤 C Nickerson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 12:49
CPC Classifications
H; H04; H04Q; H04Q3/00; H04Q3/42; H04Q3/54; H04M; H04M3/00; H04M3/60; H04M3/62
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
250 words
A central switching system serving a plurality of lines, a plurality of trunks, and at least one PBX and comprising: a communication switching network, a plurality of digit receivers, a plurality of conference circuits having at least three ports and control means responsive to calling signals from said lines and said trunks for controlling said switching system; one or more of said lines being assigned to a PBX main station directory number in the directory numbering plan of said central switching system and others of said lines being connected to PBX subscriber stations assigned calling numbers in the directory numbering plan of the PBX; and a private branch exchange attendant''s console comprising: loop circuit means individually associated with and connected to said one or more lines assigned a PBX main station directory number; manually operated key means for controlling said loop circuit means to answer incoming calls, lamp means for monitoring the states of calls completed by said loop means, an attendant''s telephone set including means for generating calling signals to identify PBX subscriber stations to which connections are to be completed; and said loop circuit means comprises means responsive to the operation of said key means and to signals generated by said central office for controlling said central office to control said conference trunk circuits, said digit receivers, and said switching network to complete connections between a calling line or trunk and a called PBX subscriber station defined by said signals generated by said means for generating calling signals.
Claim 2
Dependent Claim
250 words
A central switching system serving a plurality of lines, a plurality of trunks, and at least one PBX and comprising: a communication switching network, a plurality of digit receivers, a plurality of conference circuits having at least three ports and control means responsive to calling signals from said lines and said trunks for controlling said switching system; one or more of said lines being assigned to a PBX main station directory number in the directory numbering plan of said central switching system and others of said lines being connected to PBX subscriber stations assigned calling numbers in the directory numbering plan of the PBX; and a private branch exchange attendant''s console comprising: loop circuit means individually associated with and connected to said one or more lines assigned a PBX main station directory number; manually operated key means for controlling said loop circuit means to answer incoming calls, lamp means for monitoring the states of calls completed by said loop means, an attendant''s telephone set including means for generating calling signals to identify PBX subscriber stations to which connections are to be completed; and said loop circuit means comprises means responsive to the operation of said key means and to signals generated by said central office for controlling said central office to control said conference trunk circuits, said digit receivers, and said switching network to complete connections between a calling line or trunk and a called PBX subscriber station defined by said signals generated by said means for generating calling signals.
Claim 3
Dependent Claim
184 words
A communication switching system serving a plurality of lines, a plurality of trunks, and at least one PBX and comprising: a communication switching network for selectively interconnecting said lines and trunks, a plurality of digit receivers, a plurality of conference circuits having at least three ports, and control means responsive to calling signals for controlling said switching system; a Private Branch Exchange (PBX) comprising: an attendant''s console, a plurality of PBX subscribeR stations assigned identifying numbers in the directory numbering plan of said PBX; certain of said lines being connected to said attendant''s console and assigned a PBX main station directory number in the directory numbering plan of said communication switching system, and others of said lines being connected to said PBX subscriber stations; and said attendant''s console comprises means for answering incoming calls thereto and for generating control signals and call signaling information for controlling said switching system to complete connections through a selected one of said conference circuits between a line or trunk calling said PBX attendant''s console and a PBX subscriber station identified by calling signals generated by said attendant''s console.
Claim 4
Dependent Claim
184 words
A communication switching system serving a plurality of lines, a plurality of trunks, and at least one PBX and comprising: a communication switching network for selectively interconnecting said lines and trunks, a plurality of digit receivers, a plurality of conference circuits having at least three ports, and control means responsive to calling signals for controlling said switching system; a Private Branch Exchange (PBX) comprising: an attendant''s console, a plurality of PBX subscribeR stations assigned identifying numbers in the directory numbering plan of said PBX; certain of said lines being connected to said attendant''s console and assigned a PBX main station directory number in the directory numbering plan of said communication switching system, and others of said lines being connected to said PBX subscriber stations; and said attendant''s console comprises means for answering incoming calls thereto and for generating control signals and call signaling information for controlling said switching system to complete connections through a selected one of said conference circuits between a line or trunk calling said PBX attendant''s console and a PBX subscriber station identified by calling signals generated by said attendant''s console.
Claim 5
Dependent Claim
193 words
A Private Branch Exchange attendant''s console for generating control and call signaling signals for controlling connections to PBX subscriber stations assigned numbers in a PBX numbering plan and connected to lines of a central telephone switching system and for providing supervisory information to a PBX attendant comprising: at least one loop control circuit means connected to said telephone switching system by a line of that system which is assigned a PBX main station directory number in the numbering plan of said switching system, key means individually associated with each of said loop control circuit means for generating control signals and call signaling generating means connectable individually to said loop control circuit means under the control of said key means, and lamp means equal in number and individually associated with said loop control circuit means, and means in said loop control circuit means for selectively energizing each of said lamp means from a plurality of individual signal sources for illuminating said lamp means in a manner characteristic of the connected signal source; and means in said loop circuit means responsive to control signals received over said line for releasing said loop control circuit means.
Claim 6
Dependent Claim
193 words
A Private Branch Exchange attendant''s console for generating control and call signaling signals for controlling connections to PBX subscriber stations assigned numbers in a PBX numbering plan and connected to lines of a central telephone switching system and for providing supervisory information to a PBX attendant comprising: at least one loop control circuit means connected to said telephone switching system by a line of that system which is assigned a PBX main station directory number in the numbering plan of said switching system, key means individually associated with each of said loop control circuit means for generating control signals and call signaling generating means connectable individually to said loop control circuit means under the control of said key means, and lamp means equal in number and individually associated with said loop control circuit means, and means in said loop control circuit means for selectively energizing each of said lamp means from a plurality of individual signal sources for illuminating said lamp means in a manner characteristic of the connected signal source; and means in said loop circuit means responsive to control signals received over said line for releasing said loop control circuit means.
Claim 7
Dependent Claim
111 words
A telephone line circuit connected to a subscriber line comprising: supervisory state indicating means; a power source; gate means responsive to enable signals to connect said supervisory state indicating means to said power source; charge storage means; control means responsive to off-hook potential on said subscriber line and responsive to ringing current applied to said line for charging said charge storage means and for applying said enable signals to said gate means, said charge storage means being connected to said gate means so as to enable said gate means for a period of time after removal of said off-hook potential and after removal of said ringing potential from said subscriber line.
Claim 8
Dependent Claim
111 words
A telephone line circuit connected to a subscriber line comprising: supervisory state indicating means; a power source; gate means responsive to enable signals to connect said supervisory state indicating means to said power source; charge storage means; control means responsive to off-hook potential on said subscriber line and responsive to ringing current applied to said line for charging said charge storage means and for applying said enable signals to said gate means, said charge storage means being connected to said gate means so as to enable said gate means for a period of time after removal of said off-hook potential and after removal of said ringing potential from said subscriber line.
Claim 9
Dependent Claim
73 words
A telephone line circuit in accordance with claim 4 wherein said control means comprises diode means connected to said subscriber line so as to be conducting in the forward direction in response to the application of on-hook potential and nonconducting in response to said off-hook potential and having a predetermined reverse breakdown voltage, and said predetermined reverse breakdown voltage being of a value such that said ringing potential exceeds said reverse breakdown voltage.
Claim 10
Dependent Claim
91 words
A telephone line circuit in accordance with claim 4 wherein said control means in response to said off-hook potential on said subscriber line charges said charge storage means to a first value which is sufficient to enable said gate means for a first period of time; and said control means in response to said ringing current applied to said subscriber line charges said charge storage means to a second value which is sufficient to enable said gate means for a second period of time which exceeds said first period of time.
Claim 11
Dependent Claim
84 words
A central switching system in accordance with claim 1 further comprising: means for defining the maximum number of allowable simultaneous connections between said PBX and lines and trunks outside said PBX, means for maintaining a record of the curRent number of said simultaneous connections, and means for comparing said maximum number and said current number and for returning busy tone to further calls requesting such connections if said record of said current number of simultaneous connections equals said maximum allowable number of simultaneous connections.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-06-18 | 1976-12-18 | 1977-06-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-06-18 | 1980-12-18 | 1981-06-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-06-18 | 1984-12-18 | 1985-06-19 | $7700.00 | Window Closed / Lapsed |