The present invention provides a solution to the mobile terminal address management in the WLAN inter-working. By using the access control framework, the mobile terminal could obtain the address, and setup the tunnel together with the granting of service access. The management process would be shielded by the inherent encryption and protection of the access control process, and thus does not need extra security setup procedures to be performed. The invention also provides a method for the terminal to obtain address that binds to the session, using a fine grain service authorization procedure. The terminal could maintain multiple addresses when accessing multiple parallel sessions. The address management is also integrated with the policy control mechanisms. The policy control would provide means for the terminal and its home network to configure the WLAN when necessary after an address alternation. QoS, or tunnelling information would be modified and provisioned according to the new status using channels available in the existing policy control procedures. By this, a smooth address transition in the roaming time could be achieved, and QoS interruption could be minimized.