| 摘要 |
PURPOSE:To attain the use of a talking time display device at a terminal equipment by allowing a master equipment to detect the change in the polarity of a telephone line connected to an exchange, sending the result to a telephone set via a talking channel of a radio line, allowing the telephone set side to identify the information to apply control. CONSTITUTION:After a dial signal is sent from a cordless telephone set 5, when an opposite telephone set replies, an exchange 1 inverts the polarity of a wired telephone line 3. A polarity detection circuit 6 of a master equipment 2 detects the polarity inversion of the line 3, drives a polarity change information sending circuit 7 to send the polarity change information to the telephone set 5 via a talking channel of the radio line 4. The polarity change information identification circuit 8A of the telephone set 5 detects the inversion information to start a talking time display device 8B and to attain the talking. When the talking finished, the incoming side hooks on earlier and the line is disconnected, then exchange 1 is restored and the polarity of a sender subscriber is restored. The circuit 6 detects the polarity restoration and the restored polarity information is sent to the telephone set 5. The circuit 8A detects the polarity restoration, the device 8B is stopped to attain the use of a talking time display device at a terminal equipment. |
