The present invention relates to a wireless communication system and UE providing wireless communication services, and a method of determining the operation mode of a base station, that is, the connection mode (access mode) of a cell, based on which UE's connection is allowed by a base station in an evolved Universal Mobile Telecommunications System (UMTS) that has evolved from a Universal Mobile Telecommunications System (UMTS) or a Long Term Evolution (LTE) system, and it may be an object of the present invention to provide a process of determining the connection mode of a cell by checking the existence of a subscriber group identity if it is determined that the connection mode of a cell is not allowed for one or more UEs belonging to a particular subscriber group.