To prevent an outside line call from being disconnected due to termination of the call without performing a holding operation because a user forgets to transfer the outside line call during calling to another key telephone device.
In a key telephone system, a key telephone device 10 housing one or more outside lines and a plurality of extension lines is provided with a reservation information storage means F45 for making a reservation to automatically hold and automatically transfer the outside line call from a second key telephone set, while a first key telephone set is busy for an outside line call when the first key telephone set finishes the call; a hold control means F46 for automatically holding and automatically transferring the outside line call when the first key telephone set finishes the call; and a hole notification control means F47 for notifying by visual and audible display that the outside line call is automatically held.
OSHIMA RYOICHI
KOSAKA YUKIHIRO
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