Subscriber databases and their evolution in mobile networks from GSM to IMS

Subscriber databases are substantial points of any network. Evolution from classical telecommunication networks to NGN has changed them and also services they provide. New functionalities are required and they should fulfill more complex tasks. In this article, we present subscriber databases and their evolution from GSM network through UMTS to the newest technology IMS. This trend includes evolution from home location register and authentication center to home subscriber server and introduction of new storage architectures like XDM and GUP.