Telephone dialing apparatus
US5241590A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 18, 1990 |
| Grant date | Aug 31, 1993 |
| Priority date | — |
| Expiry date | Dec 18, 2010 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04M1/275
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A device for dialing a preprogrammed telephone number is inserted between a cord connecting the handset and body of a telephone set and either the handset or the body. In order to provide an incentive for installing the device, it is preferably incorporated in a cord detangler having a jack for receiving one end of the cord and a relatively rotatable plug for insertion in a jack in the handset or body. A push button switch on the device activates the redial function of a DTMF tone generator chip which is connected electrically in parallel with the microphone conductor pair of the cord connection. A nonvolatile redial memory is provided, either by providing battery backup for the chip so as to retain a preprogrammed number in memory even when polarization current is not available to power the chip, or by providing a read-only redial memory. The tone generator chip may include an electronic switch array through which it can detect the identity of the conductors in the cord to the handset and then establish suitable connections to the chip.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.