Telephone interface circuit
US5005199A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Nov 15, 1989 |
| Grant date | Apr 2, 1991 |
| Priority date | — |
| Expiry date | Nov 15, 2009 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04M1/715
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A line powered telephone interface circuit answers an incoming call and, responsive to a command tone, routes the call to a selected terminal. If no command tone is received within a predetermined time period, low voltage audio signalling devices located near the conventional telephone sets are activated to alert the subscriber of an incoming call. The interface need not be connected to a separated supply source. The device is connected to a telephone line and to at least one plug connectable with a telephone set jack, the device being connected to various terminals. A detector detects the ring signal and a relay establishes connection with a telephone line as soon as the ring signal has been detected for a determined time duration. A combination timer/switcher circuit inhibits the ringing of the corresponding telephone set, and is associated with a sound transducer connected operable by a low voltage signal.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.