Automatic answer/originate mode selection in modem
US4471489A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 19, 1981 |
| Grant date | Sep 11, 1984 |
| Priority date | — |
| Expiry date | Mar 19, 2001 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04M11/06
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A method and apparatus are described for automatically placing a modem in the answer or originate mode of operation without the use of a ring detector or a manually operated answer/originate mode selection switch. A timer and two latches are connected in the modem in such a fashion that when the modem is switched into operation it is in the originate mode. For a period of time determined by the timer, the modem looks for the receipt of an answer tone from a remotely located modem. If the answer tone is detected within this time, the modem remains in the originate mode and completes a handshaking sequence with the remote modem. If, however, the answer tone is not received, the modem automatically switches to the answer mode of operation and transmits an answer tone as part of the handshaking sequence.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.