The main network of tax system can be reduced to tree classes, province, city and county/tax station. It only needs to add corresponding IP voice equipments at some nodes to build intra IP Phone network.

Utilized existed BPX, using Aliwei IPPBX or analog gateways, connect FXO ports of Aliwei gateways or FXO modules of Aliwei IPPBX to traditional PBX. Connect all phone sets with FXS ports of IPPBX. Use the relay lines connected with analog gateway as number select successively, to make dialing easy. Set MCU to support telephone conference.

To where no PBX, connect FXO port of Aliwei IAD with PSTN. To county tax office or tax stations, set Aliwei 4-32 ports gateway.