Automatically controlling the operation mode of data circuit terminating equipment in a communication system
US5153897A · kind A · utility
Assignees
Inventors
Key dates
| Filing date | Jul 10, 1990 |
| Grant date | Oct 6, 1992 |
| Priority date | — |
| Expiry date | Jul 10, 2010 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L9/40
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
The operation modes of a plurality of modems in a communication system are matched with each other for connection of digital terminals to an analog telephone line on both the calling and answering sides of the analog telephone line. For example, operation modes of modems on both sides of the analog telephone line can automatically be matched with each other by transferring a mode instructing signal with DTMF, using multi-frequency DTMF symbols for a select signal employed in the telephone line, between digital terminals connected to both ends of the telephone line. More specifically, even in the case of the calling and answering sides being in different initial operation modes, the different operation modes are matched by setting a desired operation mode on the calling side and generating an off-hook signal on the answering side in response to a calling signal, followed by (1) transmitting an operation mode instructing signal in the form of a code with DTMF from the calling side to the answering side, setting the instructed operation mode on the answering side and returning if it can be set on that side, and then returning an answer tone to the calling side for completing the mode …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.