关键词: H.323, IP电话技术, 合法监听, 流量识别

Abstract: With the wide application of VoIP, how to implement lawful interception rapidly and effectively has become the focus of present research. The characteristics of H.323 network and its protocol were analyzed, and the traffic identification methodology based on H.323，the algorithm of extracting the dynamic conversation and the flow of network interception were expounded in detail. And on such basis, a design of interception model based on H.323 was put forward.

Key words: H.323, Voice over Internet Protocol (VoIP), lawful interception, traffic identification