Not sure if this is an appropriate question as it isn't directly programming related, but since understanding those is sometimes necessary for programmers, I believe it is a valid question, so I'm posting it.
Anyway, I want to learn some of the more advanced topics that you normally don't find in introductory network books, such as the ones in the title of the question. I'm mostly interested in VOIP at the moment, but the others are also of interest to me. I'd like to understand the basics beyond "MPLS applies labels with border routers", but without going into implementation specific details.