Immediately after the FastDPI started, the process to set the authorization status of all users to "unknown" is performed. This status assumes that all the user settings previously saved in the internal UDR database will be applied.

Once the network packet from the previously unknown IP address has been received, the FastDPI sends a request to authorize the User to the FastPCRF. The FastPCRF server refers to the RADIUS server, requesting from the latter the client authorization, its polycing profile (analogous to the tariff plan), and service profiles. Upon receiving a response from the RADIUS server, FastPCRF sends the user's properties to FastDPI which in turn sets the authorization status either to "authorized" (Access-Accept) or to "unauthorized" (Accept-Reject).

FastPCRF supports CoA notifications — the RADIUS server notifications about changes in user settings (for example, when the client's account has insufficient funds or the changes in band limitation have been made).