Long distance telephone call security system
US4234764A · kind A · utility
Inventor
Key dates
| Filing date | Jan 22, 1979 |
| Grant date | Nov 18, 1980 |
| Priority date | — |
| Expiry date | Jan 22, 1999 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04M1/677
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A self-contained electronic system which may be connected to either a standard dial telephone or push-button telephone for preventing use of the telephone for unauthorized long distance or toll calls. The system permits an authorized individual to key in a pre-determined security code to disable the long distance call prohibiting circuitry. In a preferred embodiment, when a "0" or "1" is detected as the first digit actuated, thereby indicating initiation of a long distance call, the telephone is disconnected from the trunk line or central office for a pre-determined time. During this time, an authorized user may input a three-digit security code to the telephone in a pre-determined sequence within a pre-determined time which will serve to reconnect the telephone to the trunk line to permit a long distance call to be made.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.