ACCESS GATEWAY AND ITS OPERATION METHOD

摘要

An access gateway (AGW) contains a subscriber IP telephone service function under an integral access device (IAD). A communication path of a PSTN network (3) side and a communication path of an IP network (4) side are alternatively formed for each of the subscribers. When the IP network (4) side has failed, switching is automatically performed to the communication path of the PSTN network (4) side.