1 Overview of the research results on “ Voice over IP

The first step for the integration of multimedia traffic within the Internet is the provision of voice services, both traditional POTS (Plain Old Telephony Services) and innovative, like multi-party audio conferences or high quality audio. Voice services in Internet are broadly indicated as VoIP (Voice over Internet Protocol), including all possible services that can be built on vocal interaction, or simply on any elementary set of provisions for the transmission of audio and voice signals (e.g., CD-quality audio retrieval from archives). VoIP services can be offered on intranets (such as a corporate network), extranets (e.g., the network of a long distance PSTN – Public Switched Telephone Network – provider), or the global Internet. VoIP applications are deemed to play an important role in the future Internet architecture, while their QoS (Quality of Service) requirements do have a major impact on the design of both the user-to-network interface and the core network architecture. In other words, VoIP requirements are one of the inputs needed for the correct design of the Internet IntServ/DiffServ architecture, that is emerging as the standard reference frameworks in Internet research.