The present invention provides, for use in telecommunication systems, a system and method enabling implementation of dynamic memory management in a subscriber identity module via an application or management system stored in the subscriber identity module. The memory regions in the subscriber identity module can be dynamically allocated to store or accommodate customers' and service providers' own applications, and the amount of information that the system operator need to store relating to the memory structures of and stored applications in subscriber identity modules that it owns or controls is significantly reduced.