Operator supervisory circuit for a key telephone system
US4029909A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Mar 23, 1976 |
| Grant date | Jun 14, 1977 |
| Priority date | — |
| Expiry date | Mar 23, 1996 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04M3/62
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A switching arrangement coupled to an operator's subset, a called party's subset, a source of key system positive ground, a supervisory indicator lamp and a line button lamp operates to light the indicator lamp when the operator's subset is taken off-hook to answer an incoming call, to cause the line button lamp to wink when the operator's subset is placed on hold to disperse the incoming call to a called party's subset, to extinguish the indicator lamp and the line button lamp wink when the called party's subset is taken off-hook and to cause the line button lamp to again wink when the called party's subset is placed on hold after the called party's subset has been taken off-hook.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.