Intercommunication and alarm telephone system
US4097690A · kind A · utility
24Cited by
4References
14Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Nov 5, 1976 |
| Grant date | Jun 27, 1978 |
| Priority date | — |
| Expiry date | Nov 5, 1996 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04M11/04
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
An intercommunication and alarm telephone system has a common control in the form of a clock driven central unit connected to an alarm control unit and one telephone line shared by a plurality of station units. The central control unit provides means for answering and placing outside telephone calls to a central telephone office, holding and transferring such calls, giving paging and intercom services, excluding and locking out other stations from outside calls, giving suitable alarms, and such other services as may be necessary or desirable.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.