As the traditional voice-centric central office bends to the pressure of diverse quality of service requirements from heterogeneous traffic types, a new network architecture is evolving that satisfies these demands. The architecture, shown in Figure 6-20, comprises a four-layer protocol stack. The Internet Protocol (IP), shown at the top, lies at the center of this great evolution. With the possible exception of the SS7 signaling protocols, IP is the world s most widely deployed protocol. It also provides us with the only truly universal addressing scheme in existence, and is embedded deeply in every network operating system deployed today that is of any consequence. It has become the focal point for such environments as call centers, where universal routing of multiple traffic types to a single operator is highly desirable. Prior to the introduction of IP and unified messaging, the ability to do that was complex, costly, and people intensive. Each operator required multiple phone lines, and the call center required call routing software that was complex and costly in its own right. IP, in concert with other Internet-derived protocols such as HTTP, allows for tremendous simplification of the call routing algorithm. Consider the following example. To contact the author of this book using every possible business contact technique, you would need an office telephone number, a fax number, a home telephone number, an e-mail address, a cell phone number, a pager number, and so on. Chances are very good that the numbers would not...