Ring detector circuit for centrally located answering and recording equipment
US4049916A · kind A · utility
14Cited by
8References
7Claims
0Family size
Assignee
Inventor
Key dates
| Filing date | Jun 20, 1975 |
| Grant date | Sep 20, 1977 |
| Priority date | — |
| Expiry date | Jun 20, 1995 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04M3/533
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A telephone answering and recording system designed 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 the centrally located answering and recording equipment. Facilities are also included which permit the customer to access the equipment from telephones other than his own regular instrument. The telephone answering and recording equipment includes a ringing signal detection means comprising an optical isolator, a comparator, and a counting means.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.