Patent ID: 8250634

Claim:
A gateway in a communications network, comprising a subscriber interface; a Session Initiation Protocol (SIP) registrar; a local cache; and a network interface in communication with the subscriber interface, the SIP registrar, a subscriber database, and a mobile device; wherein the SIP registrar is configured to: receives a first register message sent from the mobile device, the first register message including a request made by a first of a plurality of users for access to a network, wherein a separate user account is maintained for each of the plurality of users in the network and wherein any one of the plurality of users at a time can access the network by logging on and off of the network using the mobile device; and if the mobile device is not registered in the network, send a request for subscriber information associated with the mobile device to the subscriber interface, wherein the subscriber information includes a user profile for the mobile device and the user profile includes challenge information for the plurality of users; the subscriber interface is configured to: retrieves the subscriber information from the subscriber database; and send the subscriber information to the SIP registrar; and the SIP registrar is further configured to: store the subscriber information in the local cache; authenticate the mobile device based at least in part on the subscriber information; send to the mobile device challenge information associated with the first user including a password request and at least one user challenge question previously set up or selected by the first user; receive a second register message including user response information of the first user in response to the challenge information from the mobile device; authenticate the first user based at least in part on whether the user response information of the first user matches predetermined answers to the at least one user challenge question, such that the first user's airtime minutes can be used for services provided by the network that are granted specifically for the first user; and notify the subscriber interface of the authentication of the mobile device and the first user:, if the mobile device has been registered already in the network, the SIP registrar is further configured to: send to the mobile device the challenge information associated with the first user that is stored in the local cache; receive the second register message from the mobile device; authenticate the first user based at least in part on whether the user response information of the first user matches the predetermined answers to the at least one user challenge question, such that the first user's airtime minutes can be used for the services provided by the network that are granted specifically for the first user; and notify the subscriber interface of the authentication of the first user.