Abstract. This paper describes an object-oriented design and efficient implementation of 3G-324M protocol stack for real-time multimedia transmission. In particular, we discuss the implementations of 324M class hierarchical structure that includes classes H.245 (control) and H.223 (multiplexing) protocols. Our implementation is efficient and has been tested in a realistic 3G infrastructures in Hong Kong as well as in some China industries for optimizations of processing and transmission of real-time video, audio and data.