Interface system isolating a subscriber subset from a telephone switching system
US4311875A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Sep 17, 1979 |
| Grant date | Jan 19, 1982 |
| Priority date | — |
| Expiry date | Sep 17, 1999 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04M3/533
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
An interface system for installation in a centralized location remote from the customer's premises. A single line is employed in normal operation between the customer's telephone equipment and certain special use equipment such as a centrally located answering and recording equipment. The equipment may be located in a telephone central office or alternately in a separate location remote to both the customer's equipment and the telephone central office. When the equipment is in operation, the customer's phone is isolated from the telephone central office. If the customer goes "off-hook" the equipment is dropped and the customer's line is automatically connected to the incoming call.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.