Abstract: A method of connecting a line concentrator to other line concentrators in a switching system, wherein a switching unit accommodates the line concentrator is provided. The method includes the steps of analyzing a call received by the switching unit through the line concentrator, and connecting lines that are accommodated by the line concentrator and are connected to the other line concentrators without connecting through the switching unit when the call is detected to be made between the line concentrator and the other line concentrators. Thus, a call can be made to a specific dial number without connecting through the switching unit provided in the switching system. Additionally, a call can also be made by use of another switching unit when a communication path between the switching unit and the line concentrator is overcrowded.

Abstract: An IP address recognizing unit determines whether or not an IP address of a mobile IP terminal whose charging information is to be processed is managed by a local station. If the IP address is not managed, a MobileIP-Server searching unit determines which station is the home station of the IP address. Then, a different station information transmission determining unit and a different station IP charging apparatus transmitting unit transmit the charging information to the apparatus that is a different station IP charging apparatus and the home station of the IP address. Additionally, a different station IP charging apparatus receiving unit receives the charging information of the IP address, and stores the charging information in a charging information database (for different station transmission) and manages the charging information.

Abstract: A method of connecting a line concentrator to other line concentrators in a switching system, wherein a switching unit accommodates the line concentrator is provided. The method includes the steps of analyzing a call received by the switching unit through the line concentrator, and connecting lines that are accommodated by the line concentrator and are connected to the other line concentrators without connecting through the switching unit when the call is detected to be made between the line concentrator and the other line concentrators. Thus, a call can be made to a specific dial number without connecting through the switching unit provided in the switching system. Additionally, a call can also be made by use of another switching unit when a communication path between the switching unit and the line concentrator is overcrowded.