In this paper, we have focused on the problem about overload of MCU (Multipoint Control Unit) on H.323 multipoint conference systems. Conference system uses the MCU to support multipoint conference. When the number of participants increase, the MCU may become overload and it is difficult to support large scale conference by one MCU. Then if we want to have a large scale conference, we must avoid this bottle neck about load on MCU. Therefore we propose the new method called ORIO to distribute the load of MCU. ORIO doesn't use MCU for the copy of messages but each host copy the messages and play a role of MCU. Furthermore each host can find and connect to suitable one by the request routing using DNS on ORIO. We evaluated the scalability of the conference system using ORIO by measuring network load. From the result of evaluation by simulation, we find out that the conference system using ORIO has scalability for the number of hosts.