Chapter 5. VoIP Fundamentals

After reading this chapter, you should be able to perform the following tasks:

• Describe how key VoIP technologies overcome data network challenges to provide cost-efficient and feature-rich voice-enabled networks.

• Describe the key components of a VoIP network in centralized and distributed architectures.

• Develop scalable dial plans to meet both domestic and foreign requirements.

• Given the CODEC and sample size for a specific VoIP application, calculate the total bandwidth requirement, including overhead and potential bandwidth savings using voice activity detection (VAD).

• Given voice and data network statistics and network objectives, provision an appropriate amount of bandwidth for voice and data traffic.

• Describe the implications of implementing security measures in IP networks that will transport voice packets.

Voice over IP (VoIP) enables a voice-enabled router to carry voice traffic, such as telephone calls and faxes, over an IP network. This chapter introduces the fundamentals of VoIP, architecture types, and available voice-signaling protocols. Numbering plans, dial plans, and VoIP access to 911 emergency services are explained. The role of gateways and their use in integrating VoIP with traditional voice technologies is described. Traffic engineering and bandwidth calculations are discussed. Finally, the impact of security threats and the components required for a secure voice network are also explained.