| 摘要 |
PURPOSE:To perform a smooth trunk line transferring, by storing an information by which the position of a held trunk line can be identified in a storing device at the time of holding the trunk line, and by displaying it on a display corresponding to the trunk line by one to one on a called side of a calling extension speaking after holding the trunk line. CONSTITUTION:When holding a trunk line, the position of a held telephone set is read in the area of an RAM3 as a system data in a trunk line corresponding form. If an extension speaking is performed, a CPU1 confirms whether or not the trunk line is held by an extension telephone set on a calling side by the system data. If the related trunk line exists, a data controlling the light ON and OFF state of an LED which indicates the using state of the trunk line of a telephone set on a called side of the extension speaking is changed through a data LED controlling circuit 10 which lights ON only an LED corresponding to the trunk line held by the extension telephone set on the calling side of the extension speaking but not through the data showing the using state of the trunk line. At the same time, the CPU1 actuates a timer 4, and transmits a controlling signal to the LED controlling circuit 10 to return the changed data for controlling the ON and OFF of the LED of the extension telephone set to the original state, if a specified time comes. |
