Process for determining whether a subscriber is the calling or the called party
US5038373A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 22, 1989 |
| Grant date | Aug 6, 1991 |
| Priority date | — |
| Expiry date | Sep 22, 2009 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04M11/06
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A process is disclosed for the transmission of data between subscribers of a public dial telephone system in which at least a telephone, a data modem having a tone transmitter and a tone receiver, and a data device are connected to the dial telephone system. The data modem is equipped with a circuit for ringing voltage detection with bridging of ringing pauses. For transmission of a data answering tone and, if applicable, for selection of a channel position, in the case of manual operation, after operation of a data key, a distinction between the `called` state and `calling` state is made according to whether, at the start of loop current, a ringing voltage was detected by the data modem or not.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.