System Overview1System OverviewThis chapter contains the following information about VC400/VC120 video conferencing system: VoIP Principles Physical Features Packaging Contents System Component Instructions Icon Instructions LED Instructions User InterfacesVoIP PrinciplesVoIPVoIP (Voice over Internet Protocol) is a technology that uses the Internet Protocol instead oftraditional Public Switch Telephone Network (PSTN) technology for voice communications.It is a family of technologies, methodologies, communication protocols, and transmissiontechniques for the delivery of voice communications and multimedia sessions over IP networks.The H.323 and Session Initiation Protocol (SIP) are two popular VoIP protocols that are found inwidespread implementation.H.323H.323 is a recommendation from the ITU Telecommunication Standardization Sector (ITU-T)that defines the protocols to provide audio-visual communication sessions on any packetnetwork. The H.323 standard addresses call signaling and control, multimedia transport andcontrol, and bandwidth control for point-to-point and multi-point conferences.It is widely implemented by voice and video conference equipment manufacturers, is usedwithin various Internet real-time applications, such as GnuGK and NetMeeting, and is widelydeployed by service providers and enterprises for both voice and video services over IPnetworks.