A systematic approach to understanding the basics of voice over IP * Understand the basics of enterprise and public telephony networking, IP networking, and how voice is transported over IP networks * Learn the various caveats of converging voice and data networks * Examine the basic VoIP signaling protocols (H.323, MGCP/H.248, SIP) and primary legacy voice signaling protocols (ISDN, C7/SS7) * Explore how VoIP can run the same applications as the existing telephony system but in a more cost-efficient and scalable manner * Delve into such VoIP topics as jitter, latency, packet loss, codecs, QoS tools, and security Voice over IP (VoIP) has become an important factor in network communications, promising lower operational costs, greater flexibility, and a variety of enhanced applications. To help you understand VoIP networks, Voice over IP Fundamentals provides a thorough introduction to the basics of VoIP. Voice over IP Fundamentals explains how a basic IP telephony infrastructure is built and works today, major concepts concerning voice and data networking, and transmission of voice over data networks. You'll learn how voice is signaled through legacy telephone networks, how IP signaling protocols are used to interoperate with current telephony systems, and how to ensure good voice quality using quality of service (QoS). Even though Voice over IP Fundamentals is written for anyone seeking to understand how to use IP to transport voice, its target audience comprises both voice and data networking professionals. In the past, professionals working in voice and data networking did not have to understand each other's roles. However, in this world of time-division multiplexing (TDM) and IP convergence, it is important to understand how these technologies work together. Voice over IP Fundamentals explains all the details so that voice experts can understand data networking and data experts can understand voice networking. The second edition of this best-selling book includes new chapters on the importance of billing and mediation in a VoIP network, security, and the common types of threats inherent when packet voice environments, public switched telephone networks (PSTN), and VoIP interoperate. It also explains enterprise and service-provider applications and services.