To provide a high speed line service at a metered rate by connecting a subscriber's line and a high speed line as needed.

When a subscriber B10 sends a line connection request to an exchange 11, the vacancy of the high speed line is inquired to a line state holding part 18 by a line state monitoring part 15 comprising a controller 14 of the exchange 11. The use status of the high speed line is grasped by the line state holding part 18 and the vacant state of the high speed line is reported. When the high speed line is vacant, a connection control part 16 instructs to connect the subscriber's line of the subscriber B10 to the high speed line to a line switching device 12. According to the instruction from the connection control part 16, the subscriber's line of the subscriber B10 is connected to the high speed line by the line switching device 12.