Adopt distributed structure to whole voip network based on the current ip network. Utilized the current bandwidth resource, do not need to change current network structure.

In province Bank, set GK, set Aliwei IAD in province Bank or city branch Bank. If possible, set sub GK in city branch Bank. IP phone can be set at any node.

Aliwei IAD can realize transfer between IP phone and PSTN. Realize dial long distant phone and the other part where have branch Bank only pay local fee.