An arrangement to accomplish authentication of end-users (1) and end-points (1) in a packet based network, which includes components that support all or parts of different versions of the H.323 recommended standard, be proposed. Authentication is accomplished by means of an authentication proxy (2), which will support security profiles supported by one or more associated gatekeepers (3). Provision of end-user (1) and end-point information for an authentication proxy (2) may be accomplished by means of standard non-proprietary communication and protocol such as http or https and a simple html form, an applet or a servlet respectively, and for a gatekeeper (3) by means of a RAS message such as gatekeeper request (GRQ).