A method and a system for collecting session-specific event data in a telecommunications network where sessions are connected through a number of network entities which generate event data and have mutual signaling connections. The objective of the invention is to provide a solution whereby event detail records relating to one session but generated by a number of different network entities are sent in a centralized manner in real-time to a given collecting network entity. Thus, the event data combination is optimized and the unnecessary transmission of event detail records from one collecting network entity to another is avoided.