| 摘要 |
PURPOSE: A private branch exchange service(PBX) is provided to allow a call connection service between private networks having a dial number different from each other at subscriber's side without passing through a wide area network(WAN). CONSTITUTION: A WAN includes a subscriber's side(20) provided with a PC(21) and a communication terminal such as a first and a second telephones(22_1,22_2) and a central office(30) provided with a digital subscriber multiplexing apparatus(31), an ATM exchanger(32), a gate way(33) and a switching system(34), A PBX without passing through a WAN interval by using a VOIP device and an interval duplexing system is characterized in that an integrated access device(IAD)(10) is installed between the subscriber's side(20) and the digital subscriber multiplexing apparatus(31) so as to manage a telephone number such as an input, a deletion and a comparing connection of telephone numbers, therefore, the communication terminal such as the PC(21), the first and the second telephones(22_1,22_2) of the subscriber's side(20) is communicated to each other through the IAD(10) without passing through the WAN, By duplexing the digital subscriber multiplexing apparatus(31) of the central office(30) and the IAD(10), although one of the WAN lines between the digital subscriber multiplexing apparatus(31) and the IAD(10) is fail, it is possible to communicate through the other connection line.
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