For the reconfiguration of a radiotelephone unit including components programmable in configuration modes, the invention provides a removable electronic device having stored data defining a plurality of configuration modes which is connected to the apparatus. A configuration mode is selected from the apparatus in the device. The programmable components are programmed by the device and reconfigured in accordance with the selected configuration mode data under the control of the device. The data of the configuration modes can be downloaded from a server into the device through a downloader terminal.