Abstract: An apparatus for charging a network subscriber's prepaid network usage account in real time. The apparatus has a service engine, a service manager and a quota manager. The service engine is operable to analyze network traffic flow through the apparatus and to identify a network transaction corresponding to the account. The service engine is further operable to determine a usage quota for the subscriber. The service manager is operable to maintain information related to the subscriber and the account. The quota manager is operable to communicate with an external prepaid server.