Electronic key telephone system
US4160131A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 7, 1977 |
| Grant date | Jul 3, 1979 |
| Priority date | — |
| Expiry date | Oct 7, 1997 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04Q11/0407
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
An electronic key telephone system is disclosed that provides a plurality of telephone features and functions, while only requiring a four-wire line between the central equipment and each key-set telephone (KST) and a two-wire line between the central equipment and each single-line telephone (SLT). Linear delta coding and time division multiplex (TDM) techniques are used to eliminate the multiple pairs required in traditional private business exchange (PBX) systems between the remote key telephones and the control unit. In the present system, a microprocessor controlled TDM controller transmits and receives control signals serially to and from interfaces in the system for control purposes and also for establishing exchange of digitized audio information data between selected interfaces. The system thus exchanges digitized audio information directly between interfaces and provides control signalling between the TDM controller and the interfaces, with all of the exchanges being done in real time. Among other things, the system is compatible with all types of existing central office exchange lines. The system may use combinations of single-line telephones (SLTs) or key-set telephones …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.