the invention relates to a method for classifying traffic flows in a packet - based wireless communication system , said packet - based wireless communication system comprising at least one radio access network and a packet - domain core network , said method including the step of analyzing at least one data packet of at least one traffic flow through deep packet inspection at the level of the core network in order to classify the traffic flow . in order to save resources by enabling selective deep packet inspection , it is proposed that the method further comprises the steps of determining whether or not a data packet relates to at least one context out of a set of predetermined critical contexts , wherein the context is a function relating data packets to selected users , selected areas , and / or selected services , and selecting the at least one data packet for deep packet inspection if the data packet relates to one of said predetermined critical contexts .