Milestones:First Real-Time Speech Communication on Packet Networks, 1974 - 1982
First Real-Time Speech Communication on Packet Networks, 1974 - 1982
In August 1974, the first real-time speech communication over a packet-switched network was demonstrated via ARPANET between MIT Lincoln Laboratory and USC Information Sciences Institute. By 1982, these technologies enabled Internet packet speech and conferencing linking terrestrial, packet radio, and satellite networks. This work in real-time network protocols and speech coding laid the foundation for voice-over-internet-protocol (VoIP) communications and related applications including Internet videoconferencing.
Street address(es) and GPS coordinates of the Milestone Plaque Sites
MIT Lincoln Laboratory: 244 Wood St., Lexington, MA 02421 US (42.458626, -71.263568)
- Site entrance gate is on Wood St. at Schilling Circle
- Plaque location: Main Lobby (42.45913, -71.26700)
Details of the physical location of the plaque
One of 6 Milestone plaques on a display board prominently located in the Main Lobby
How the plaque site is protected/secured
Building security is next to the display board; viewable during normal business hours
Historical significance
This pioneering work on speech in packet networks developed and demonstrated systems which were forerunners of the voice-over internet protocol (VoIP) systems that are now so widely in use. The real-time voice work included development of a new Network Voice Protocol (NVP), because the packet and reliability constraints of the available Transmission Control Protocol (TCP) implementation made it unsuitable for real-time communication. This protocol development was an immediate forerunner of the separation of TCP and IP, so that the real-time packet speech work played a large role in the development of the protocols, which are still in wide use today. The technology and protocols for real-time speech over packet networks also enabled other real-time internet applications such as packet video, so that now systems like Skype enable real-time voice and video at home and in offices for extremely large number of people.
This work combined major developments in multiple areas, including the first real-time implementations of narrowband LPC speech coding on digital signal processors, network protocols to enable real-time packet delivery, strategies for reconstituting speech, techniques for reconstitution of speech from packets arriving at non-uniform intervals, packet speech conferencing techniques, and interoperation over different types of packet networks (landline, Ethernet, satellite, radio). Another feature was the outstanding collaboration among organizations and across technology areas. Finally, the long-term impact is a major feature which sets this work apart, as evidenced by the wide use of VoIP and related application such as packet video.
References and Further Reading
Cohen, “RFC0741: Specifications for the Network Voice Protocol,” 22 Nov 1977.
M. Gray, "The 1974 origins of VoIP," IEEE Signal Processing Magazine, Vol. 22, July 2005, pp. 87-90.
Robert M. Gray, Linear Predictive Coding and the Internet Protocol, NOW Publishers, 2010
Packet Speech was featured both in a Special Issue of the IEEE Journal on Selected Areas in Communciations (1983) and in an IEEE Press Book (1990). Both included papers on the milestone accomplishments featured in this nomination.
W. P. Lidinsky, D. Vlack (editors), Perspectives on Packetized on Packetized Voice and Data Communication, IEEE Press, Piscataway, NJ, USA 1990, ISBN:0879422637 (This 1990 IEEE Press also contains three of the papers above, as well as a number of other papers on packet speech and data).
Letter from the site owner giving permission to place IEEE milestone plaque on the property
Proposal and Nomination
Milestone-Proposal:First Real-Time Speech Communication on Packet Networks
Milestone-Nomination:First Real-Time Speech Communication on Packet Networks
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