The Home Subscriber Server (HSS)-subscriber database is the primary subscriber database that contains subscriber and authentication information required for the 3GPP subscribers to access the WLAN interworking service. The SBR Carrier matches data received in the authentication/authorization request with the information in the HSS-subscriber database. If a match is found and the subscriber’s credentials are correct, then the SBR Carrier accepts the request. If no match is found or a problem is found with the credentials, the SBR Carrier rejects the request. The HSS-subscriber database also stores the primary profile data which is downloaded by the SBR Carrier for policy decisions.
The SBR Carrier coordinates with other SBR Carriers through a registration mechanism in the HSS-subscriber database. The first SBR Carrier that authenticates a particular subscriber is registered as the “responsible” server in the HSS-subscriber database. Any subsequent authentications for that subscriber will be redirected to the “responsible” server, as long as it remains registered. After the subscriber has left the network, the registration may be purged by the SBR Carrier or the HSS-subscriber database. Once the subscriber joins back, the “responsible” server is again elected.