Introduction to IP Telephony: Why and How Companies are Upgrading Private Telephone Systems to use VoIP Services, Second Edition

This book explains why people and companies are converting some or all of their existing (legacy) telephone systems from dedicated telephone systems (such as proprietary PBX) to more standard IP telephony systems. These conversions allow for telephone bill cost reduction, increased ability to control telephone services, and the addition of new telephone information services. Through the use of IP telephony service, companies can immediately reduce their telecommunication costs 40% to 70%. This book provides an overview of the different types of IP Telephony systems including IP PBX, IP Centrex and Internet Telephone systems. You will learn the key functional parts of voice over IP systems and how voice over Internet protocol (VoIP) systems work. Explained are the processes used to setup and control IP telephony service. The common IP Telephony protocols including session initiation protocol (SIP), Media Gateway Control Protocol (MGCP) and H.323 are described as well. You will learn how to connect telephones through data networks using adapters or by using telephones that plug directly into data networks (IP telephones). Discover what equipment and service choices you have and how they can affect your costs and service quality. Find out how packet losses and packet delays creates distortion and operational challenges and ways to reduce or eliminate these effects. Advanced telephone features that are only possible through IP Telephony are described along with how customers can setup and configure their equipment through the use of self provisioning web portals. Learn about the different types of services, their typical costs and some of the hidden costs of IP Telephony and ways to reduce or avoid them. Some of the most important topics featured are: • The different types of IP Telephony systems • Functional parts of VoIP systems • The processes used to setup and control IP telephony service • How to connect standard telephones through data networks • What choices you have and how they can effect your service quality • Advanced telephone features that are only possible through IP Telephony • The different types of services and their typical costs • Some of the hidden costs of IP Telephony