Video-mediated communication systems such as teleconferencing and videophone have become popular. As with face-to-face communication, non-verbal cues such as gaze, facial expression, head orientation and gestures in visual systems play an important role. Existing systems, however, do not support mutual gaze because the lay-out of the camera and monitor is restricted. Thus, conversations using visual systems differ from those in face-to-face communication. This paper clarifies the problems of the video-mediated system, specifically for comparing the system with communication using eye-contact and with communication using no-eye-contact. This study focuses on the protocol of opening communication, e.g. establishment of a visual-audio link, person identification and confirmation of the acceptance of conversation. We conducted experiments using the two systems. Analysis of recorded video sequences revealed that the system using communication with eye-contact induced behavior similar to th...