A control apparatus (4) is configured to perform a network-level discovery including tracking current locations of first and second radio terminals (1A, 1B) to detect proximity of the first and second radio terminals (1A and 1B). The control apparatus (4) is configured to acquire at least a location history of the first radio terminal (1 A) before starting the network-level discovery triggered by a request for the network-level discovery issued from the first radio terminal (1A). It is thus, for example, possible to improve accuracy of a determination whether to start network-level discovery (e.g., EPC-level ProSe Discovery).