| 摘要 |
PURPOSE:To attain the connection of an external terminal connected securely 1:1 to a trunk line by providing plural terminals for connecting an external terminal on at least two trunk lines among plural trunk lines respectively. CONSTITUTION:A using state detection part 104 is securely connected to a terminal 106 having a trunk line interface through a connector 116 provided on a main device 101. Moreover, a using state detection part 105 is securely connected to a terminal 107 having a trunk line interface. With such constitution, the terminals 106 and 107 can communicate each other with use of trunk lines 102 and 103, and the communications are in the secret calling state by a control part 109. When the terminals 106 and 107 do not use the trunk lines 102 and 103, a key telephone system not shown in the figure can use the trunk lines 102 and 103. |
