A mobile data communications device includes: a reconfigurable user identification module operable to store at least a current primary mobile identity, the mobile device being operable to provide mobile data communication via a mobile network subject to the primary mobile identity being authorized with the mobile network; and a detector to detect the user identity of a current user of the mobile device; the mobile device being operable to access a mobile identity database which provides a mobile identity to the reconfigurable user identification module for use as the primary mobile identity, in response to the detected user identity of the current user of the mobile device.