Communications of the ACM
Successful multiparty audio communication over the Internet
Communications of the ACM
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Certain teleconferencing applications must host very large number of participants that exceeds the capacity of a single mixing media server. Traditionally multiple media servers are connected in a cascading arrangement to meet the capacity requirement. This paper discusses the shortcomings of the traditional approach such as lower audio quality and unfairness of speaker selection. It then presents a novel approach that exploits the exibility of Voice-over-IP and the Session Initiation Protocol to move participants between a main conference mixer and one or more media-distributing replicators as their role change between active talk-listen and listen-only. Benchmarking of an implementation of the replicators on general-purpose computers shows that large capacity can be achieved without specialized hardware. Moreover, it is shown how this approach can augment an already deployed teleconferencing system without modifying the existing telephony features, thereby illustrating the power of modularity and application composition in the SIP servlet environment.