US3715516A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Line circuit for key telephone system
Assignee: Nortel Networks Ltd
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Filing: 1971-06-17
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Granted: 1973-02-06
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Expires: 1991-06-17
Abstract
Abstract A line circuit for interfacing subscriber sets of a key telephone system with a telephone line terminating at its other end in a central office or a private branch exchange. The line circuit embodies a novel approach in this particular field, utilizing logic building blocks to condition two control means performing functions associated with such systems. The approach is well suited to MIS components and technologies.
Inventors
- 👤 J Ebrahimi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 12:48
CPC Classifications
H; H04; H04M; H04M9/00; H04M9/002; H04M9/005; H04M9/006
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
226 words
A line circuit for controlling the connection of a subscriber set in a key telephone system to a telephone line, comprising: first and second control means each having first and second operating positions to provide four operating configurations; and a binary logic means responsive to an idle condition of said telephone line and said subscriber set for conditioning said first and second control means in a first operating configuration to indicate said idle condition; said binary logic means also being responsive to an incoming ringing signal, containing a succession of ringing bursts and ringing pauses, on said telephone line for conditioning said first and second control means in a second operating configuration to indicate an incoming ringing signal condition; said binary logic means including a discriminator network for delayedly responding to said incoming ringing signals, and a multi-function time-out circuit for maintaining said ringing condition during said ringing pauses; said binary logic means also being responsive to an off-hook condition of said subscriber set for conditioning said first and second control means in a third operating configuration to indicate a busy condition of said telephone line; and said binary logic means also being responsive to initiation of a hold signal from said subscriber set to condition said first and second control means in a fourth operating configuration to indicate a hold condition of said telephone line.
Claim 2
Dependent Claim
226 words
A line circuit for controlling the connection of a subscriber set in a key telephone system to a telephone line, comprising: first and second control means each having first and second operating positions to provide four operating configurations; and a binary logic means responsive to an idle condition of said telephone line and said subscriber set for conditioning said first and second control means in a first operating configuration to indicate said idle condition; said binary logic means also being responsive to an incoming ringing signal, containing a succession of ringing bursts and ringing pauses, on said telephone line for conditioning said first and second control means in a second operating configuration to indicate an incoming ringing signal condition; said binary logic means including a discriminator network for delayedly responding to said incoming ringing signals, and a multi-function time-out circuit for maintaining said ringing condition during said ringing pauses; said binary logic means also being responsive to an off-hook condition of said subscriber set for conditioning said first and second control means in a third operating configuration to indicate a busy condition of said telephone line; and said binary logic means also being responsive to initiation of a hold signal from said subscriber set to condition said first and second control means in a fourth operating configuration to indicate a hold condition of said telephone line.
Claim 3
Dependent Claim
226 words
A line circuit for controlling the connection of a subscriber set in a key telephone system to a telephone line, comprising: first and second control means each having first and second operating positions to provide four operating configurations; and a binary logic means responsive to an idle condition of said telephone line and said subscriber set for conditioning said first and second control means in a first operating configuration to indicate said idle condition; said binary logic means also being responsive to an incoming ringing signal, containing a succession of ringing bursts and ringing pauses, on said telephone line for conditioning said first and second control means in a second operating configuration to indicate an incoming ringing signal condition; said binary logic means including a discriminator network for delayedly responding to said incoming ringing signals, and a multi-function time-out circuit for maintaining said ringing condition during said ringing pauses; said binary logic means also being responsive to an off-hook condition of said subscriber set for conditioning said first and second control means in a third operating configuration to indicate a busy condition of said telephone line; and said binary logic means also being responsive to initiation of a hold signal from said subscriber set to condition said first and second control means in a fourth operating configuration to indicate a hold condition of said telephone line.
Claim 4
Dependent Claim
226 words
A line circuit for controlling the connection of a subscriber set in a key telephone system to a telephone line, comprising: first and second control means each having first and second operating positions to provide four operating configurations; and a binary logic means responsive to an idle condition of said telephone line and said subscriber set for conditioning said first and second control means in a first operating configuration to indicate said idle condition; said binary logic means also being responsive to an incoming ringing signal, containing a succession of ringing bursts and ringing pauses, on said telephone line for conditioning said first and second control means in a second operating configuration to indicate an incoming ringing signal condition; said binary logic means including a discriminator network for delayedly responding to said incoming ringing signals, and a multi-function time-out circuit for maintaining said ringing condition during said ringing pauses; said binary logic means also being responsive to an off-hook condition of said subscriber set for conditioning said first and second control means in a third operating configuration to indicate a busy condition of said telephone line; and said binary logic means also being responsive to initiation of a hold signal from said subscriber set to condition said first and second control means in a fourth operating configuration to indicate a hold condition of said telephone line.
References Cited (Backward Citations)
US3420961A
Cited
US3604857A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-02-06 | 1976-08-07 | 1977-02-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-02-06 | 1980-08-07 | 1981-02-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-02-06 | 1984-08-07 | 1985-02-06 | $7700.00 | Window Closed / Lapsed |