A system, conferencing application, and graphical user interface for supporting standards based, multiparty teleconferencing, video conferencing, and application sharing are disclosed. The system includes a hardware platform such as a desktop computer, a network computer, or a workstation computer. The hardware platform includes one or more processors, and a system memory as well as input and output devices for user interaction. Conferencing hardware such as a microphone and speakers for audio content and a video camera for video content are interfaced to the hardware platform, typically through an I/O bus of the hardware platform. The system further includes operating system software residing at least in part in memory. The operating system controls execution of application programs on the hardware platform. The system further includes an application for participating in a multi-party conferencing session. The conferencing application generates a graphical user interface that includes a call control section for managing an active conferencing session, a phone control section, including video windows displaying video content of one or more parties to the conferencing session, and a mode section for facilitating access to another conferencing system.