I got this book at Interop as part of a package, attending Professor Held's lecture they gave me the book. The book is really good, it covers IP and Frame Relay, telephonre operations and shows how to transport voice over both. It even includes examples of economic analysis that I found extremely usefull as I had to do this to get my project approved. The only area where improvement is required is that Professor Held's lecture included many practical application notes concerning latency that were not in the book. By the way, he provides his email address and responds to requests, so he might provide you with this usefull information.