Chapter 6. Introduction to IP-Based Real-Time Communications

6.1. Introduction

This chapter introduces the reader to voice over IP (VoIP) and multimedia over IP. Although IP communications networks support a wider spectrum of services than voice calls, the technique for transporting voice via the Internet is used as a reference model. This chapter serves as a preamble to the subsequent chapters, where the principles of VoIP are placed into network context, such as the Session Initiation Protocol (SIP) and IP Multimedia Subsystem (IMS). Understanding VoIP may be considered a prerequisite for understanding IMS. Throughout the coming chapters (SIP, IMS), we will utilize and refer to the basics of VoIP.

6.2. Basics of Voice Over IP

When considering “voice ...

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