| 摘要 |
PURPOSE:To solve a trouble to caller and to improve serviceability, by recalling a trunk line incoming call to an original transfer extension when the transferred extension of the trunk line incoming call does not answer within a fixed time. CONSTITUTION:When a transfer is instructed from an extension telephone set 1a, a central controller 6 stores the central office trunk number in an area corresponding to the extension telephone set to which the instruction of the transfer of a memory area is issued. Simultaneously, the controller 6 sends a dial tone urging dialing to the transferred extension to the extension telephone set 1a which becomes the transfer source. When the value of an RNA timer times up, the controller 6 finds the extension telephone number of the extension telephone set 1a which is the transferring source from the memory area and recalls the holding trunk line incoming call to the telephone set 1a which is the transferring source. As a result, the speech path between the extension telephone set which is circuit-connected first and the trunk line can be reformed effectively without giving any excessive burden to the operator of an attendant board.
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