Disclosed herein is a two-level, network-based application control (NBAC) architecture for monitoring services provided via a packet-based network. The NBAC architecture includes a Network Trigger System provided at a network level to analyze data flows relating to services to be monitored to detect occurrence of configurable events, and to generate and send event reports; and a Usage Status Engine provided at a control level to configure the Network Trigger System to detect occurrence of events of interest, and to receive and process the event reports from the Network Trigger System to monitor the services.