Although the chapters in this book could be read sequentially, the organization allows you to focus your reading on specific topics of interest. For example, if you already posess a strong telephony background, you could skim through the first couple of chapters, which offer a review of fundamental telephony concepts, and concentrate your study on the remaining chapters. Specifically, the chapters in this book cover the following topics:
Chapter 1, "Introduction to Voice Technologies" This chapter introduces you to traditional telephony networks and telephony concepts. Additionally, the building blocks of packet telephony networks are addressed.
Chapter 2, "Analog and Digital Voice Connections" This chapter expounds on much of the content in Chapter 1 (for example, analog and digital connections) by examing the interworkings of telephony operations at an electrical level. Also, this chapter discusses strategies for overcoming specific challenges in a VoIP network (for example, the transmission of fax and modem tones).
Chapter 3, "Voice Interface Configuration" This chapter discusses how to attach a Cisco voice-enabled router to existing telephony devices, such as a PBX or an analog phone. This chapter also covers the syntax required to configure analog and digital voice ports.
Chapter 4, "Voice Dial Peer Configuration" This chapter shows you how to add call routing intelligence to a Cisco voice-enabled router through the use of "dial peers." Since dialed digits might need manipulation under certain circumstances (for example, adding a 9, a 1, and an area code when sending a call out over the public switched telephone network [PSTN]), this chapter discusses multiple digit manipulation techniques.
Chapter 5, "VoIP Fundamentals" After the preceeding chapters lay a strong foundation for how to construct a basic VoIP network, this chapter discusses potential challenges and design considerations associated with sending voice across an IP-based network. For example, the bandwidth required to successfully transmit voice varies based on such factors as voice sample size, Layer 2 encapsulation, and voice coding/decoding algorithm (that is, "CODEC").
Chapter 6, "VoIP Signaling and Call Control Protocols" As VoIP networks grow larger, designers must understand the characteristics of call control protocols that set up calls between VoIP devices. Specifically, this chapter covers the theory and configuration of the H.323, SIP, and MGCP call control protocols.
Chapter 7, "Improving and Maintaining Voice Quality" Simply adding VoIP packets to an existing data network can result in unacceptable voice quality from an end user's perspective. Therefore, this chapter addresses the quality challenges associated with a VoIP design and discusses various Cisco quality of service (QoS) mechanisms to help mitigate these challenges. While the configuration of QoS mechanisms is a study in and of itself, this chapter introduces the reader to a feature called AutoQoS, which can help administrations apply a robust QoS configuration to both router and switch platforms, with a minimum amount of configuration.
This book concludes with two appendixes and a glossary. Appendix A, "Answers to Chapter Review Questions," provides the answers to the review questions that appear in each chapter. Appendix B, "Cisco VoIP Applications," describes several implementations of VoIP networks. The glossary defines important terms you encounter throughout the book.
