A mobile communication network system is provided in which when a radio system is selected from plural types of radio systems as a radio system for use in paging, the optimum radio system for the mobile terminal to be paged can be selected. When it is selected, traffic does not concentrate on a specific radio system, or no excess delay occurs when the mobile terminal starts communications. When the mobile communications network system performs paging as a paging notification to a mobile terminal through any one of various radio systems under a communications environment in which radio waves of various radio systems having different communication systems are used, a radio system is selected from a plurality of radio systems depending on the application used in the communications of the paging requested mobile terminal and a paging operation is performed through the selected radio system when a paging request is issued.