The videoconferencing applications transmit video and audio data through data networks. The current networks such as the Internet are heterogeneous: their subnets may possess different bandwidths. When a videoconference covers subnets of different bandwidths, multiple video coding schemes of different bandwidth requirements can be used at the same time to make good use of the bandwidth resources. Sometimes difference of host processing power also leads to using multiple video schemes. In this paper, we discuss multiple video transport sessions of multi-video-scheme ( i.e multiple video scheme) videoconferencing applications. Video data in different schemes must be transmitted over different multicast trees. Thus the multi-video-scheme application creates multiple video transport sessions. We describe the architecture for the multi-video-scheme videoconferencing application as an open system. It consists of mono-video-scheme subsystems with some gateways. Gateways translate and forward video data between the mono-video-scheme subsystems, and forward audio data between these subsystems. We discuss translation for different video schemes in two way: direct conversion, and «first to decode then to encode». Finally we present a multi-video-scheme videoconferencing application IVS-H261/JPEG on the Internet. IVS-H261/JPEG consists of two mono-video-scheme subsystems IVS-H261 and IVS-JPEG with a gateway IVS-SERV.