I don't think so. Most of the forums say no, and cite the fact that gmail allows for unlimited voice calling with Google Voice and hangouts, which I know is not the same... Here's one link: https://groups.google.com/forum/#!topic/chromebook-central/WZ_N7m6xvfk
But, the magicJack Plus apparently requires no computer at all.
So if you don't mind having to have your computer open and on all the time and having to basically 'talk in to the computer', just go ahead and use the built in Google calling capability, but if keeping your computer open and on all the time is an issue then I'd go with one of the devices, like magicJack Plus, that uses your wireless but doesn't depend on a computer. It kind of seems like we're getting to the point where using both is redundant.