Parallel-connected dialing signal transmission inhibiting device for data transfer over a telephone link
US6711238B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Jan 22, 1999 |
| Grant date | Mar 23, 2004 |
| Priority date | — |
| Expiry date | Jan 22, 2019 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04M1/715
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A parallel-connected dialing signal detection and transmission-inhibiting device is disclosed which detects dual-tone multi-frequency dialing signals across tip and ring conductors of a telephone link and switches in an a.c. load that attenuates the dialing signals by at least 30 dB. This prevents action in response to the DTMF signals by a central office servicing the telephone link, thereby allowing commands-data to be transmitted within the home telephone wiring. Such commands can be used to invoke a speed/auto dialing function, to provide an intercom, to control appliances, etc. To allow fast response, the controller charges a capacitor of the a.c. load by connecting it across the tip and ring conductors in response to an off-hook condition. Then it is disconnected to allow a dial tone to reach a user at the telephone. Further transparency is provided by the fact that a single interfacing capacitor connects both the dialing signal detector and a tone generator to the tip line. This reduces the loading on the tip line by the device during periods when users are conversing on the telephone link.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.