A method for incorporating subscriber identity data into a subscriber identity module involves the subscriber identity module being incorporated in ready-to-operate condition in an end device. The subscriber identity module is arranged to manage a plurality of subscriber identity data and to receive subscriber identity data, and the subscriber identity data is stored in a file system. The method includes receiving a load command from a subscriber identity data management in the subscriber identity module; preparing the file system in the memory area of the subscriber identity module for storing subscriber identity data; receiving subscriber identity data in the subscriber identity module; storing the subscriber identity data in the prepared file system; and checking the data integrity of the received subscriber identity data by the subscriber identity module.