neration (2G) and third generation (3G). ANSI-41 defines the communications that must be used to support inter-MSC handoffs, roaming, and the short message service (SMS). It also contains functions for operations, administration, and maintenance (OA&M) and over-the air service provisioning. ANSI-41 is crucial to 3G network design and operations because it defines how CDMA networks will communicate with the Internet and other data networks around the world. Although ANSI-41 officially sets the standard only for interoperability between networks, in reality, it functionally defines the core aspects of every CDMA cellular system. In Chapter 16, "Call States," we introduce a practical design and troubleshooting tool, the state diagram. As we introduce the tool, we also provide models of landline and cellular call states for traditional telephone calls, call waiting, and three-way calling. If you are not already familiar with state diagrams, you will find that they help engineers define problems clearly, speeding the way to a solution. The capacity of any system is limited by the capacity of its weakest link, its bottleneck. While CDMA is the technology of the air interface between our subscriber's cellular telephones and our network, an optimized CDMA radio link will not solve all our capacity or quality problems. With a deep understanding of telephony, we can design and implement optimal cellular networks not only at the base station but also at the MSC and in the backhaul network that connects the base stations to the MSC. 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. Source: CDMA CAPACITY AND QUALITY OPTIMIZATION Chapter The PSTN and Telephone Switching Telephone switches are the core of the public switched telephone network (PSTN). It is hard to imagine a telephone system without switches, although there was one on Wall Street about 100 ye