th. Historically, given the choice of protecting their existing service margins or allowing new markets to emerge based on new models, service providers choose what they are most comfortable with-protecting existing service mar- gins. Now they are changing the way they view this because of the suc- cess of text messaging and other applications, but they still have a long way to go. For all intents and purposes WAP is dead. Wireless data faces a number of significant challenges, each of which could become a showstopper. First, most wireless data networks are designed as overlay IP networks, reflecting the ongoing evolution from circuit to packet architectures in the public network. Unfortunately, these designs don't integrate seamlessly with the preexisting PSTN. Second, spectrum limitations severely limit the number of voice chan- nels that can be provisioned as well as the amount of bandwidth that is available for data. Low bandwidth applications such as SMS and IM serve the market adequately for the time being, but over time-and not all that much time-higher bandwidth applications such as multimedia messaging (including video and still images), gaming, and multiuser col- laboration applications will drive the demand upward. Mobile gaming alone is expected to grow from 7.9 percent of the user base actively play- ing games wirelessly to 35 percent by mid-year 2008. Third, broadband users (cable and DSL) have come to expect always- on connectivity. Because of current spectrum limitations, most wireless players will, because of cost and spectral scarcity, drop broadband con- 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. Access Technologies Access Technologies nections after a period of inactivity. This will reduce the perceived effec- tiveness and value of the service in the minds of customers. It's a well- known fact that always-on broadban