A holder for a mobile communication device

A holder for a mobile communication device, the holder comprises an identification interface for coupling to a Subscriber Identification Module (SIM), a mobile communication network module arranged to manage a connection to a mobile communication network, a Personal Area Network (PAN) module arranged to manage a connection to the mobile communication device and an audio module adapted to enable input and output of audio signals. The holder / sleeve or cover for a mobile communication device provides additional functionality using a SIM connected to the holder. Voice calls can be facilitated using the audio module and the mobile network in combination with the SIM, while the wireless PAN module enables communication with the mobile device. The device may thus receive data from and send data to the holder, for example to display information relating to the operation of the holder or to facilitate control of the functionality of the holder through the mobile communication device. An application is loaded on the mobile device to provide an interface with the holder with communications being managed between holder and device using the PAN (e.g. Bluetooth (RTM)) or WI-FI (RTM)).