Is IMS The Answer? (2008)

By Bruce P. McLeod, Cox Communications, Inc.

Is IMS the answer? The 3GPP IP Multimedia Subsystem is a topic of hot debate among technologists in the MSO community as to its validity as a service integration platform and core technology. It is regarded by many as a solution looking for a problem and by others as a panacea for simplifying the rapid introduction of new service types that have voice as a key component. This paper discusses the real world learning garnered by Cox Communications during our technology research and prototype development beginning in 2006 and throughout 2007. Specifically addressed will be the strengths and weaknesses of Session Initiation Protocol as an enabling integration technology and the challenges of providing next generation voice services in a world where the rules of the Public Switched Telephony Network still define much of what can (and can’t) be done with new voice services.

Communications Technology has been on an evolutionary path to convergence since the need to transmit computer data from one computer to another arose in the mid twentieth century. The telephone network was adapted to support transmission of data. At the same time pure data network technology evolved and over time. With the advent of internet technology it was recognized that voice service could be considered as just another data type and in many ways could be transmitted within a data network as effectively as any other data type and Voice over IP was born. Voice over IP technology has begun to replace traditional Public Switched Telephone Network elements across the globe. In most successful cases this transformation has gone un-noticed by the end user. This apparently seamless evolution has transpired because the design of VoIP technology has followed a path of replication of telephone service to a handset. In the future, the traditional telephone handset will remain part of the Voice service network but it will not be the only interface as it has been for over 100 years. The voice interface of the future may be a video screen, mobile PDA, a utility within a web page, or possibly something that is difficult to imagine today. IP Multimedia Subsystem is a technology that lends itself to integrating Voice to other application types. But is it the best answer for how to do this? This discussion analyzes the known requirements for voice services and how IMS addresses those.

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