Talking about the catchy title of this post, the technology used by Onavo is VPN, which you should remember from previous posts. In contrast to the post mentioning HideMyAss, Onavo offers its VPN more or less for free. They don't advertise it as "Look, people! We have free US VPNs for you", but in the background they're using a US VPN in order to accomplish their goals (read, data compression).
So, if you are planning to use US-only services (like Google Voice), install Onavo's app, set it up and you're good to go. However, according to this page, they're planning to make this a paid service in the future. So hurry up!