Patent ID: 6980554

Claim:
A switching system including a switching unit and a line concentrator, said switching unit comprising: a number-analyzing unit that analyzes a dial number notified through said line concentrator; a line-selecting unit that selects lines that are accommodated by said line concentrator and are connected to other line concentrators, a number-analysis table including trunk-group numbers initially registered for dial numbers that are used for connecting the line concentrator to the other line concentrators, a line-selection table including a chain of idle trunks corresponding to a trunk-group number selected from said number-analysis table by said number-analyzing unit by use of said dial number and to a line-concentrator number of the line concentrator accessed by said dial number, said line concentrator comprising a line-connecting unit that connects said lines, wherein said line-selecting unit selects the lines and directs said line-connecting unit to connect said lines together when said number-analyzing unit determines that said dial number is used for connecting said line concentrator to the other line concentrators, thereby connecting said line concentrator to the other line; and wherein said line-selecting unit selects an idle trunk connecting said lines from said line-selection table by use of said trunk-group number and said line-concentrator number.