Hold circuit for telephone
US4011413A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jan 12, 1976 |
| Grant date | Mar 8, 1977 |
| Priority date | — |
| Expiry date | Jan 12, 1996 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04M1/80
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
An electronic hold circuit for a telephone. A single sensing and latching module is connected across the telephone lines, and is adapted to sense the voltage present on the telephone lines to distinguish between on-hook, off-hook and hold conditions. The hold feature is engagable by one or more hold signaling modules disposed, for example, near each telephone and extension telephone in the system. Each hold signaling module comprises a switch associated with a level establishing device, for establishing a voltage on the telephone lines at a level intermediate the relatively high on-hook voltage and the relatively low off-hook voltage. The sensing and latching module responds to this intermediate level by latching the telephone lines at a voltage sufficiently low to maintain the connection with the called or calling party.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.