| 摘要 |
PURPOSE:To omit the trouble of dial operations of a calling subscriber, by releasing the line when busy tone is detected and by starting again to transmit a number on the basis of contents of the memory unit and repeat call. CONSTITUTION:When calling subscriber 1 hooks off the telephone receiver, subscriber's circuit 2 detects start, and dial tone is returned to calling subscriber 1. Meanwhile, subscriber's circuit 2 sends start information to control unit 4, and exchange 6 not only relays the continuous dial number of calling subscriber 1 but also stores it in memory unit 5 temporarily. If busy tone is detected by busy tone detector 3, this information is transmitted to control unit 4 to release the line. After completing release, control unit 4 starts exchange 6 to read out the called subscriber number in memory unit 5 and transmits the number to wait for answer. However, if busy tone is detected, the same operation is repeated. When called subscriber 7 answers, the serivice state is set, and control unit 4, memory unit 5, and so on are released. |
