| 摘要 |
PURPOSE:To eliminate the need for addition of a trunk line number display function and a display device to an incoming display panel by operating dial operation of a special code at the calling from a private branch of exchange and selecting a trunk line trunk of a trunk line number known and determined in advance. CONSTITUTION:A trunk line trunk 2 and an extension telephone set 3 are connected to the private branch of exchange 1. An extension adaptor memory 4 stores a trunk number determind at each extension telephone set 3. When a dial number from the extension telephone set 3 is received, the received dial number is discriminated and whether or not a special code exists before a general dial number is discriminated. When the special code exists, the trunk line number stored in the extension adaptor memory 4 is read and a designated trunk line trunk is selected. When no special code exists, the trunk line trunk of general idle state is selected. When the trunk line trunk is selected, the trunk line connection is executed. If the trunk line trunk selection is failed, a busy tone connection operation is executed. |
