This is all true. One technicality though is that Google Voice is not a VOIP solution (yet) which is why the fight with ATT over terminating rural calls is interesting.
I think the clarification is that it is not just a VOIP service. If I call someone with my Android phone it is routed through normal voice call paths, not as a VOIP call.
Yes I almost included that caveat. "Google Voice" is really a collection of products. Those products have the common feature that they mainly deliver voice traffic to the PSTN. That is what I meant by "not a VOIP solution." But yes, the in-browser calling product within GMail should be considered a VOIP product. It is distinct though from something like Skype which is primarily VOIP with an option to terminate to the PSTN. The Google Voice set of products is primarily a way to connect to the PSTN.
