Automatic line supervisor for use with a call concentrator
US4503290A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 19, 1982 |
| Grant date | Mar 5, 1985 |
| Priority date | — |
| Expiry date | Apr 19, 2002 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04M3/5166
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
An automatic line supervisor is disclosed for a telephone system having a line concentrator which converges a plurality of subscriber lines into a single output line to a telephone answering service (TAS) which is coupled to the concentrator by a telephone line with automatic ring down (ringing tie line). In order for the line to properly operate after the TAS has answered a subscriber call, and gone back on hook, the telephone concentrator must be disconnected from the ringing tie line and from the caller. In a first embodiment, the automatic line supervisor is an integral part of the concentrator and operates to make the requisite disconnection of the concentrator from the ringing tie line and the caller on a subscriber line by monitoring the tie line for appropriate audio tones, generating a control signal either in response to the presence of a dial tone for a particular time interval or in response to the absence of DTMF tones (dual tone multifrequency) for a particular time interval. The control signal is used to open appropriate relays to disconnect the line concentrator from the caller and the ringing tie line to prepare the ringing tie line for ringing the TAS that another…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.