VoIP for all

I’m looking for either a book, or resource on the net that will explain VoIP from a perspecive that those comfortable with the voice side of a network will understand how it takes voice circuits & converts them into data circuits. Hopefully, this reource will also do a revers, that is to say, allow those comfortable with data circuits how voice circuits differe from data and thus what factors need to be cosidered when converting voice lines into suitable bandwidth, so that in the end, both sides of the house have a better understanding of how the other side operates, so that we can ultimately build a better VoIP network.