Authentication, authorisation and accounting for a roaming user terminal

摘要

A method of Authentication, Authorisation and Accounting ('AAA') for services performed when a user terminal (1) registered at a home AAA server (3) in its home domain (2) is visiting another AAA domain (4) ('roaming'). An AAA message element (14) is sent from the user terminal (1) to an AAA server (6) in the visited AAA domain (4) comprising a user identification code (15) and a codification (16) combining the user identification code (15) with a common time-varying code element (10). The common code element is initialised by the home AAA server (3) and is available at the user terminal (1) and at the visited AAA server (6). The visited AAA server combines the user identification code (15) with the common time-varying code element (10) and compares the combination result with the codification (16) received from the user terminal to verify the AAA message element. <IMAGE>