There is provided a network system and its associated devices and techniques which allow a terminal device to utilize functions of another terminal device without the need to provide any dedicated interface or system switch. A server 12 receives a service request from a first terminal device 13 or a second terminal device 16 while the first and second terminal devices 13 and 16 are in voice communication with each other. Upon receipt of the service request, the server 12 searches position information on the second terminal device 16 from an identifier contained in the service request to specify a processor 18 located in the neighborhood of the second terminal device 16 on the basis of the position information. Then the server 12 establishes a new connection (communication lines 2B and 2C) for image communication. Thus the image data is transferred from the first terminal device 13 to a reception device 17 through the communication lines 2B and 2C, and displayed on a large screen of the processor 18.