Portable field control unit for emergency telephone communications
US4354058A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 24, 1980 |
| Grant date | Oct 12, 1982 |
| Priority date | — |
| Expiry date | Jun 24, 2000 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04M5/00
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A portable field unit for conducting and controlling emergency telephone communications, particularly in hostage situations, is disclosed. Three telephone lines and a monitoring line can be connected to the unit, which can function as a miniature manually operated central office. A prime operator can control a first line and a common line, while a backup operator can control a second line and the common line. The backup operator can monitor the prime operator's line, and the prime operator's line can also be remotely monitored. The first line and the common line can be patched together by the prime operator for direct communication between them. A privacy switch is provided under the prime operator's control to produce a masking tone in the monitoring circuits when a private communication between the first line and the common line is desired.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.