es circuit switching technology, where lack of equipment interoperability between the cus- data networks are built packet-switched technology. tomer premise and the equipment vendor There are various reasons this transition is taking place, lack of standards defining the acceptable levels of many of which have to do with economies of scale. Tra- quality for voice transport over a carriers' frame ditionally a Telephony network has been architected relay network. around circuit switch technology, requiring specific equipment and management techniques. Networks have These trade-offs do not necessarily negate the value and emerged from being difficult to implement, a side promise of VoFR. Significant advances in digital signal thought for many companies to a critical part of their processors and compression algorithms often provide business strategy and an integral part of their economic voice at a level approaching toll quality, for a fraction of growth. the cost of public service. VoFR vendors continue to add The overall advantage of VoIP comes from treating advanced capabilities in management and administration voice as another form of data. While claims that the capabilities. In addition, future industry work will also PSTN is dying are premature and unfounded, the ad- seek to develop standards which define acceptable levels vantages presented by IP telephony are clearly visible of quality and performance metrics for voice transport today. through carriers' frame relay networks. More bandwidth Voice over Internet Protocol One advantage of VoIP is that it dramatically improves the efficiency of bandwidth for real-time voice trans- One of the greatest challenges for VoIP is to develop mission, in many cases by a factor of 6 or more. This networks that are not only scaleable but also seamless to increase in efficiency is a real long-term driver for the the subscriber and to the service provider. If the service is evolution from circuit-switched to packet-switched difficult to access by the subscriber due to complex 