Conventionally, in a system where devices for handling multiple media data such as audio and video are present, there is a problem that the number of audio channels that can be processed at the gateway is limited. In light of this problem, this invention offers a gateway having distributed processing function for a telephone or a data processing system featuring the capability to request address conversion to another terminal within the system to replace the address of stream-type packet data such as audio and video meant for itself, and if the aforementioned terminal to which the request was sent responds that it can handle the requested processing, to notify the address of the terminal processing the address conversion to the terminal transmitting the stream-type packet data.