| 摘要 |
PURPOSE:To simplify the operation of a repeated extension call in a telephone exchange device by enabling the extension call without a break when a dial outgoing leaving an off-hook as it is performed after the completion of the extension call. CONSTITUTION:When either of telephone sets 4 performs an on-hook according to the completion of the call during the extension call through an extension circuit between the telephone sets 4, it is detected by a loop detection circuit 13. According to the generation of the detecting output of the no-hook, a control circuit 15 turns on a corresponding one out of switches SWa1-SWn1, and sends an outgoing tone from a signal tone generating circuit 18 to the extension circuit and also, an extension outgoing waiting state responding to the detecting output from the circuit 13 corresponding to the telephone set still in the off-hook state is generated, and therefore, the dial outgoing by an extension number from the telephone set which continues the off-hook is permitted instantly.
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