on VoIP, i will recommend the following 2 books from cisco press:
1.Voice over ip Fundamentals, by Jonathan Davidson and James Peters
2.Integrating Voice and Data Networks, by Scott Keagy.
the topics you are inquiring about are not covered in so much details, but there are one or 2 chapters dedicated to giving you an idea where to start, and some notes will point you to where to find more on the specific topic. Also try searching cisco's Knowledge Base. If you have extra time, also hit this site: www.protocols.com and www.howstuffworks.com.
hope it helps
E.