A hierarchical data structure for signaling and data handling at a packet core network is defined. A hierarchical data structure is applied to both persistent and dynamic information to support a type of devices that share the same characteristics. Subscription database, context information, and policy rule information is comprised of group level information and device level information. Group level information contains the information the devices that belong to the group share. Device level information contains the device specific information that is different from group level information. When a device belonging to a group requests access to a packet network or performs a procedure that changes the mobility or session state of the device, context management unit works with authentication unit, subscription database unit, and policy decision unit to construct a right information for the device to handle the control and user data traffic.