A user terminal device stores user information in a memory, and stores constant data in another memory. The user terminal device selects one or more other equipment to be combined suitably for use with the service equipment, based on the model information and operational conditions of the service equipment as well as the stored constant data. Then, the user terminal device transmits the user information and the selection information to the host computer, and requests display permission from the host computer for displaying the selection information onto the display section. The selection information is displayed on the display section only when the display permission is obtained from the host computer. Thus, workload on the host computer end may be reduced. In addition, the host computer does not fail to obtain the user information.