| 摘要 |
PURPOSE:To grasp a trunk line number in personel use by selecting and catching a trunk line corresponding to a trunk line designating transmission discriminating signal, and connecting it to an extension subscriber. CONSTITUTION:An extension subscriber EXT dials a trunk line designating transmission discriminating signal provided separately from a trunk line automatic transmission discriminating number, in order to execute directly a trunk line transmission by using a trunk line number 2110. A control device CONT receives the trunk line designating transmission discriminating signal from an originating register trunk ORT, and executes a busy test of a trunk line trunk COTO corresponding to the trunk line number 2110 which is made to correspond in advance to this number. When the line is disengaged, switching to a path of the trunk COTO - a channel switch NW - a subscriber's circuit LC is executed, the extension subscriber EXT and the trunk COTO are connected, and the transmission to the trunk line is executed. Thereafter, a dial tone from the trunk line can be heard, and the EXT can know that the trunk line number 2110 is being used. |
