A portable radio communication device has an exchangeable cover. Specifically the invention relates to a system of a mobile phone to provide multiple functionality and user interoperability to a mobile terminal device. The present invention provides a mobile communication device cover comprising a keyboard and a cover processor. The keyboard and the cover processor are interconnected. The cover is characterized by a bus interface, for connecting the cover processor to a mobile communication module, wherein the bus interface is adapted to operate with a plurality of mobile communication modules.