This paper describes Zakim, the multimodal teleconference system used at the World Wide Web Consortium \cite{W3C}. While the system presented here does not make use of advanced research work, the technology presented have been developed with robustness in mind, as it is used almost round-the-clock by several hundred people. The context and requirements are introduced first, followed by a description of the system's features. Lastly we describe how the structure of W3C teleconferences has been modified by the use of this system, and discuss some issues and possible improvements.