A method in a cellular mobile packet data network is provided composed of four main steps. These are capturing raw traffic traces over standardized interfaces of an operational cellular mobile data network, parsing through the traces in order to extract and correlate all the information, which is needed to build a traffic and session database, defining a set of appropriate key performance indicators, and calculating the above defined key performance indicators. A system in a mobile data network is also provided, the key element of which is a traffic and session database, which correlates traffic and mobility information extracted from passively captured traces collected from standardized interfaces. A set of key performance indicators describing the true, user perceived end-to-end quality of the most commonly used applications is also listed.