An embodiment of the invention includes initially registering information with a data system, wherein the registered information pertains to a user of a mobile device and includes credential information, and further includes a message address associated with the user. An enrollment request, together with the specified credential information, is sent to a management server. Responsive thereto, the server sends a message of specified type to the message address associated with the user, wherein such message includes a pin code. The pin code is then sent from the device to the server, and responsive to receiving the pin code, the server is operated to deliver a security token, for use in authenticating the mobile device to selectively access the particular data processing system.