How will this contribute to getting MagicJack to work?

Can a Virtualbox Ubuntu leave one USB Jack working in Windows and the
rest on Ubuntu to accomplish this task?

A better solution would be to get the MagicJack to work under Ubuntu
on the USB port. But so far I haven't been able to accomplish that
yet. Some more time may help with this though, because it would be an
ideal solution for a phone service in North America.