! Interoper- ability among these providers has always been a problem, but a few com- panies, including Verisign, are stepping up to the challenge of creating an IM interoperability gateway and putting it into service. Summary The added function of managing value-added services is a critical differ- entiator: Consider that AT&T's professional services business is now a $4 billion product line. Consider also that the true professional services firms (Deloitte, for example) are in enormous demand by telecom indus- try players to help them navigate their way through the stormy waters Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Telecom Market Segments Telecom Market Segments of market recovery, product positioning, competitive positioning, and value delivery. One key to success is the ascendancy of the seven-layer value chain that I described in an earlier book. Because of positive reader response, I repeat that discussion here in a somewhat amended form. In the early 1960s, American psychologist Abraham Maslow proposed his now-famous five-layer hierarchy of basic human needs. In it, Maslow ranked the basic human needs: physiological demands; security and safety concerns; love and feelings of belonging; competence, prestige, and esteem; self-fulfillment; and finally, curiosity and the need to understand the surrounding world. Maslow concluded that these basic requirements had to be fulfilled before the higher level, more cognitive demands could be fulfilled. Interestingly, there is a similarly structured hierarchy-of-needs model within the domain of telecommunications, particularly as it relates to the activities of network designers, service providers, and manufacturers of components and network devices. This hierarchy, comprises a seven- layer model with these identified layers, starting from the bottommost layer: features; functions; benef