This book is a practical guide to telephony configurations that are based on VoIP protocols such as SIP, Skinny and H.323. The chapters provide an explanation of the protocols, the content of which is supported by packet captures, network topologies, real world examples, calculations, devices and analysis. Each chapter will explain the protocol basics, the fields displayed in packets and important points such as where the packets came from and operation. Where appropriate, chapters will have sections for security risks and mitigation. The objective is to provide an explanation of what is seen and a context. Readers will gain an unparalleled understanding of these fundamental networking components and so this book will also serve as a good basis for coursework that is less applied in nature.