Narrowcasting - Controlling media policy in SIP multimedia conferencing

Media and the vectors of its transmission is private information and should be made available only to authorized participants in a conference. In a traditional conference system, users' voices might by default be shared with all others, but a participant might want to select a subset of the conference members to send his/her media to or receive streams from. We review the concept of narrowcasting, a technique for limiting such information streams in a multimedia conference, and propose manipulation of media policies in centralized conferencing systems in a sip framework. This system allows each participant to flexibly select another participant or group of participants for media transmission using existing standard protocol (sip) for configuring fine-grained narrowcasting sessions.