Institute for Telecommunication Sciences
the research laboratory of the National Telecommunications and Information Administration

James A. Hoffmeyer

Abstract: This report discusses quality–of–service (QOS) issues for telephone networks. Deregulation and divestiture have fostered increased competition in the United States in the telephone equipment and service industries. There are many economic, policy, and technical issues that remain to be solved as the result of the plethora of equipment and services now available. This report addresses the technical problems associated with the interconnection of equipment from many vendors. In order to maintain a satisfactory quality of service to the end user, performance standards must be developed, approved, and implemented. The work of IEEE, CCITT, and ANSI–accredited standards groups responsible for telephone QOS is reviewed. The problem of interconnecting different national networks in the international community is seen to be analogous, in part, to the problem of interconnecting the numerous public and private networks within the United States. Although progress has been made by both national and international telephone QOS standards groups, unsolved issues remain. Principal among these are the development of objective measures of voice quality, the mapping of these objective measures into five levels of quality, enhancement of IEEE and CCITT telephony QOS standards (including the development of standards for the transmission of data on voiceband networks), and the development of QOS standards for Integrated Services Digital Networks. These are discussed in this report along with recommendations for new programs that would contribute to their resolution.

Keywords: competition; divestiture; objective quality evaluation; quality of service; subjective quality evaluation; telephone systems standards

To request a reprint of this report, contact:

Lilli Segre, Publications Officer
Institute for Telecommunication Sciences
(303) 497-3572

Disclaimer: Certain commercial equipment, components, and software may be identified in this report to specify adequately the technical aspects of the reported results. In no case does such identification imply recommendation or endorsement by the National Telecommunications and Information Administration, nor does it imply that the equipment or software identified is necessarily the best available for the particular application or uses.

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