This book is organized logically with material advancing gradually. You can reference the various sections and chapters according to your needs and interests. If you have a good understanding of VoIP and IPT technology and tasks involved in PDIOO methodology, you might want to browse through Part I and spend more time on Part II. Part II references the appendix materials as appropriate, so you will have to refer to these appendixes quite often and will find them extremely useful.
This book provides several references and web links to useful material that is readily available and beyond the scope of this book.