Method and system for extending and/or modifying functionality of a platform for a product, such as a mobile terminal for a wireless telecommunications system. The system includes a platform domain having a software services component for providing functionality, and an interface component having at least one interface for providing access to the software services component for enabling application software to be installed, loaded and run in said platform via the at least one interface. The system also includes plug-in software for use together with the application software for extending and/or modifying the functionality of the software services component of the platform domain via the at least one interface.