Abstract: Protocols of H.223 and H.245 for multimedia communications on PSTN are discussed. It analyses the main functions and theoretically the main design problems forthe protocols.The main program flow charters are given, and the methods for design problems are also given. According to the above program flow charters and design methods, we realize the protocols, and verify that the protocols are basically in accordance with ITU-T specifications.

Key words: public switched telephone networks, multimedia communication, mean waiting time