still haven't heard back from my friend at lucent but I saw a couple blog posts that say simultaneous voice and data is acheieved becasue the carrier can move the voice to the data channel via VOIP. So it's like having a cable modem (data which carries voice) not dsl (voice and data alongside each other).
here's a link that says the same thing- so that might be the case:
http://www.dailywireless.org/2006/06...do-reva-ready/