An interface for a mobile communication device is provided, including at least one memory unit configured to store read/write data associated with transaction accounts, at least one user interface software application, and at least one contactless communication protocol application. A radio frequency identifier unit having an antenna communicates with a radio frequency identifier reader through a contactless transaction account communications channel distinct from a mobile communications channel of the mobile communication device. An input/output interface unit communicates with a corresponding input/output interface unit of the mobile communication device and provide access to and control of the at least one memory unit and the radio frequency identifier unit by a processor of the mobile communication device.