Abstract: The registration at a terminal on the basis of registration data which are stored in a terminal memory and the need to deregister oneself subsequently at the same terminal has the disadvantage that, if the deregistration is forgotten, the terminal memory is unnecessarily occupied by invalid information. This is prevented if the deregistration is performed from a further terminal, the possibilities including both an explicit deregistration and an implicit deregistration on the basis of a further registration. If the registration data are split into identification data and terminal data, more efficient use is made in that case of the terminal memory and if the identification data are split into user data and service data the possibility even arises of deregistering a user at a particular terminal for some services but not for other services.