Microcomputer controlled key telephone line circuit
US4382163A · kind A · utility
9Cited by
6References
6Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Jul 27, 1981 |
| Grant date | May 3, 1983 |
| Priority date | — |
| Expiry date | Jul 27, 2001 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04M9/006
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A microcomputer controlled key telephone line circuit for use in a key telephone. A microcomputer is used to sequentially and alternately scan the ringing leads and tip and ring leads associated with connected line circuits and A leads associated with connected telephone stations. The microcomputer operates in response to changes in the status of these leads to control the normal key telephone functions such as line pickup, hold and ringing current detection, lamp illumination and tone signaling.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.