A method for treating a subscriber data list of the subscriber identity module of a mobile station in a linear memory of the subscriber identity module, and a subscriber identity module and a mobile station. A directory structure is formed in the memory of the subscriber identity module with the aid of a directory separator. The directory separator is for instance the symbol “/”. Then for instance in the GSM system a “name” located in the “directory” is represented according to the directory structure as a term “directory/name” in the linear memory of the subscriber identity module, but the user treats the list of numbers by directories, and most preferably in an alphabetical order.