Abstract: The present invention provides a telecommunication apparatus, user equipment and method for Single Sign-On authentication purposes when the access network does not provide data origin authentication. The invention proposes the re-utilisation of the original access authentication carried out with the core network, namely with the home network holding the user's subscription or with the visited network where the user is roaming. Therefore, access credentials obtained during a successful authentication of the user with the core network are linked at the user equipment side with a secure tunnel established towards a service network through the access network. Said access credentials received at an entity of the service network are also linked therein with the secure tunnel, and both linked with an internal IP address to securely identify the user in the service network.

Abstract: An authentication server (e.g., AAA server) is described herein which is located in a CDMA2000 network and used to authenticate a user terminal that is connected to a non-CDMA2000 network. The authentication server receives an access request for authenticating the user terminal connected to the non-CDMA2000 network. Then, it obtains a root secret key shared between the user terminal and the CDMA2000 network and generates a GSM or UMTS-like authentication vector which is used to authenticate the user terminal according to a GSM or UMTS-like authentication method. The access of the terminal to the non-CDMA2000 network is granted upon successful authentication. According to embodiments of the invention, the non-CDMA2000 network can be a WLAN network, and the authentication methods used can be EAP SIP or EAP AKA. The present invention allows one to use authentication servers that were originally intended for WLAN-3GPP interworking scenarios also in WLAN-CDMA2000 network interworking.