 and services. In many ways, SIP enabled networks are the key to universally-available mobile multimedia services, offering the standards-based infrastructure that will allow many latent Smartphone features to be activated and integrated into a host of consumer and business applications. Session Initiation Protocol As discussed earlier in Chapter 7, SIP (Session Initiation Protocol) is a signaling protocol for Internet delivered applications including Internet voice and video conferencing, Push-To-Talk (PTT) and PTT over Cellular (PoC) telephony, presence, events notification, and Instant Messaging (IM). In the most basic terms, SIP is a set of standard Internet protocols designed to connect any fixed or mobile SIP-enabled client devices to any Web-delivered application server any other remote SIP-enabled client. From the perspective of mobile solutions, SIP ensures an integrated IP environment for mobile devices to securely and reliably communicate with each and any IP-enabled application. As the IETF's standard for multimedia communications over IP, SIP is a text-based, application-layer control protocol (defined in RFC 2543) that can be used to establish, maintain, and terminate sessions between two or more end points. SIP is in some respects comparable to HTTP, although service creation methods based on SIP have been defined to provide enhanced addressing and extensibility features for Video Communications: The Whole Picture delivering applications throughout the entire mobile 3G architecture. SIP can also be used in a wide host of application areas but is uniquely suited for setting up enriched communication sessions such as a real-time video/voice calls (sounds like videoconferencing to me!) between mobile devices. SIP has been globally selected as the call set-up protocol for all IP networks that will be standardized by the Third Generation Partnership Project (3GPP). This means that 3G All-IP terminals and networks will support SIP. SIP and Java-Refreshing Technology for the Mobile World Mobile applicatio