ilable for wider use. The IRTF p2p and SAM research groups are dedicated to corresponding work. 6.2.4 Mobile Group Members Mobile end systems today escort people from puberty to old age. Standard systems such as mobile phones or PDAs, but also specialized gadgets, i.e., gaming stations or dedicated professional equipment, must be increasingly C 2009 by Taylor & Francis Group, LLC Group Conference Management with SIP considered as people's primary access devices to information, communication, and entertainment. At the same time, most of public and private spaces have turned into areas of ubiquitous network operations. Wireless Internet con- nectivity is offered by a 3GPP or IEEE 802.11 WLAN infrastructure, but emerging 802.16 environments and mobile ad hoc network (MANET) mesh networks have started to complement the established access networks. Voice calls dominate the mobile market, gradually complemented by selec- tive video services. Mobile telephone operators are on the spot of migrating to entirely IP-based fourth-generation networks in accordance with 3GPP release eight standard track. SIP has been selected to play a dominant role in both: provider-centric architectures based on the IP Multimedia Subsys- tem (IMS) and provider-independent end-to-end session signaling, the latter being particularly obstructed by NAT and port barriers in the mobile regime. As SIP/IP 2-way dialogs are expected to dominate the mobile world soon, demands for conferencing are likewise foreseeable. Mobile group conferences meet multipoint transmission capabilities in virtually all wireless technologies, e.g., in 802.11 and 802.16, in DVB-H, as well as in 3GPP, which defines the Multimedia Broadcast and Multicast Services (MBMS) in release 6. Issues of providing seamless communication services under mobility-related handovers remain though on Internet Protocol layers. They will require an explicit han- dover management whenever provider or IP subnet addresses change between attachments. Schemes for achieving a seamless mobility mana