| 摘要 |
PURPOSE:To eliminate a troublesome redialing operation to realize a trunk line call back system, by providing a means to store all digits of a trunk line dial. CONSTITUTION:When the output side trunk lines COT1-COTn are all busy with a private telephone exchange, the all digits of a dial number suplied through a standard telephone 1 or a key telephone 2 are stored in a storage device 9. Then an idle trunk line is secured if the idle line exists among the trunk lines of the output side, and at the same time a call back signal is sent to the calling telephone to which the above-mentioned dial number is supplied. When an answer of the callin telephone is detected to the call back signal, the all digits of the dial number stored MEM in the previously secured trunk line are sent. Thus a calling subscriber has just to perform the registration of a call back and has not to operate the dial again in case an idle trunk line is available. |
