Today, many audiovisual delivery systems, including video streaming and videoconferencing, are being developed for use over a range of networking technologies, the differing characteristics of which pose problems for service level interoperability. Multimedia transcoding is one means to provide interoperability between different types of audiovisual terminals and between terminals that connect to different networks. This paper describes a flexible multimedia transcoder that enables service interoperability between different types of terminals across heterogeneous networks. In particular, the target of this development is to connect to H.323 client and OdBits servers from a client application in mobile terminals via the developed multimedia transcoder.