Overview

The ISDN-UP and TCAP sections of this book briefly covered some of the features and enhanced services made possible with SS7 signaling. In this section we look at some of these applications from a broader, end-user perspective. From this perspective, we stand to gain a better understanding of the benefits that SS7 signaling provides for both individuals and organizations.

Until the widespread adoption of SS7, the advanced features the telephone company developed were limited for use out of one central office; these advanced features are commonly named Centrex. Many private businesses obtained their advanced features and custom applications by purchasing a mini telephone switch for their building; most commonly called a private branch exchange (PBX) or private automated branch exchange (PABX), and lastly stand-alone computer telephony (CT) systems linked buildings together, but not farther than a few blocks apart.

With the introduction of SS7 systems and the Intelligent Network (IN), many new broader applications are possible. The significant advantage of SS7-based applications is realized when the services are offered city wide, county wide, or even nationally. The standardized services now enhanced by SS7 signaling are offered under the common name Custom Local Area Signaling Services (CLASS).

Beyond the local area, SS7 also provides signaling connectivity for enhanced services spanning the nation. Nationwide SS7 provides service intelligence for applications such as Network-based Voice Messaging and Network-based Automatic Call Distribution. Network-based enhanced services all require specific centralized databases containing the unique information for processing the enhanced application.

Figure 9.1 shows the...