sil Contact: FIGURE 6.10 Call flow of extending established group sessions to a new party. central and distributed conference management using unicast or multicast. Special focus is donated to the emerging field of mobile user agents, which are expected to soon populate daily usage and require seamless integration. Presently available and developing mobility schemes promise to assist roam- ing conference members at real-time compliant handovers in an end-to-end fashion. SIP offers widespread potential for supporting group formation and com- munication, while the field of optimizing multi-peer sessions is under active current investigation. Comprising peer-to-peer technologies, as well as applica- tion layer and source-specific multicast, this outline explores the rich solution space of future directions in infrastructure-assisted or purely peer-managed conferences. Lightweight solutions adaptive to heterogeneous environments and varying scenarios are discussed. It is the hope of the authors to stimulate an active development of new applications that admit rich functionality and substantial deployment. References [1] Jonathan Rosenberg, Henning Schulzrinne, Gonzalo Camarillo, Alan Johnston, Jon Peterson, Robert Sparks, Mark Handley, and Eve Schooler. 2002. SIP: Session Initiation Protocol. RFC 3261, IETF, June. C 2009 by Taylor & Francis Group, LLC SIP Handbook: Services, Technologies, and Security [2] Jonathan Rosenberg. 2007. A Hitchhiker's Guide to the Session Ini- tiation Protocol (SIP). Internet draft-work in progress 04, IETF, November. [3] IAB and IESG. 2000. IETF Policy on Wiretapping. RFC 2804, Internet Engineering Task Force, May. [4] Mark Handley, Van Jacobson, and Colin Perkins. 2006. SDP: Session Description Protocol. RFC 4566, IETF, July. Jonathan Rosenberg. 2006. A framework for conferencing with the Session Initiation Protocol (SIP). RFC 4353, IETF, February. [6] Alan Johnston, ed. 2007. Session initiation protocol service examples. Internet draft-work in progress 13, IETF, July. [7] Jonathan Rosen