This paper deals with two closely related issues: — Characteristics of multimedia conferencing, and the typical bandwidth requirements for audio, video, and data, including text, still images, and graphics. — Results of an investigation examining how an end-to-end asynchronous transfer mode (ATM) network architecture can satisfy the stringent requirements of multimedia conferencing. The delay within the network has been calculated to estimate the upper-and lower-delay budgets for the video codec, to ensure that the end-to-end transmission delay is not perceptible to users. For some service categories, bandwidths have been estimated that will satisfy these nonperceptible delay limits, mean opinion score (MOS) performances, and response-time requirements for real-time multimedia conferencing.