A method, computer program product, and apparatus for reconstructing sessions on a network are described. The method allows for monitoring of quality of service at an application level as well as for understanding application specific events. This allows the method to be used to generate service detail records for usage based on application type for use in billing. It also allows the qualitative and quantitative analysis of quality of service based on application specific parameters. For example, for voice over IP calls, application events like adding participants and removing participants can be detected and billed accordingly. Also, the quality of service can be measured. For example, the actual latency can be compared to a predetermined latency amount set by a provider for voice over IP calls. Additionally, service detail records can be generated based on application specific events instead of generic flows, so usage billing can be performed based on factors such as a price per minute per leg, etc, with application specific events generated each time a leg is added or dropped.