Telephone line/subscriber equipment disconnect apparatus
US4489221A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 23, 1982 |
| Grant date | Dec 18, 1984 |
| Priority date | — |
| Expiry date | Aug 23, 2002 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04M3/301
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A disconnect signal (e.g. 130 volts D.C.) is applied at the telephone central office to the tip and/or ring lines. A latching relay adjacent to the subscriber equipment operates directly responsive to the disconnect signal, i.e. without delay normally caused by capacitive or voltage buildup, to disconnect the line between the tip and/or ring lines to which the signal has been applied and the subscriber equipment. The relay simultaneously connects the signal to ground through a relatively large resistance to identify or confirm to the central office that the switching action has occurred, which in turn is indicative of line continuity. The relay also operates in a similar manner responsive to a reverse polarity signal (e.g. the re-establishment of the normal line voltage of -48 volts D.C.) to re-establish a normal operative condition.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.