| 摘要 |
PURPOSE:To find the cause of busy tone disconnection by making the busy tone to be sent to a user without fail when the compulsory disconnection of a call is performed according to no presence of a coin. CONSTITUTION:When the coil to be contained is not present, a coin containing part (CRC) 1 detects that and so that, according with the state, a control circuit (CNT) 6 makes the transistor Q1 of a loop control circuit (LCT) 3 of, a reversing loop including a call circuit (TKC) 4 is released and the state is held. Therefore, because the function of an exchange is restored to a non-reversing state, the exchange performs always the sending of the busy tone and the busy tone is sent to the receiver R of the TKC4 and it is heard by the user and so, the user can recognize that the call is disconnected due to the shortage of the coin to be thrown.
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