The present disclosure relates to a method related to an online charging system for a cellular radio communication system. The method includes obtaining a notification that a refill action of a user account for the communication system is pending. The notification includes an identifier (vid) of a refill resource for the refill action. The method also includes inspecting a refill database updated by an account management function of the online charging system to determine whether the refill resource identifier is included therein, indicating whether or not the user account has been refilled based on the refill resource.