OpacityZero,
Google is filtering some international ip addresses. To date no one in South America has reported anything that would indicate an issue with that. So far AFAIK units are in service in the following Latin countries:
Bolivia, Peru, Mexico, Brasil
There may be other OBi units in service in some other locations in Central/South America. It would be interesting to hear where some of these units are located.
Before buying and sending a unit down, configure everything in the USA. Setup a GV account. Make a test call to his from his computer to your phone using that GV account. If it works, then the OBi should be able to work as well.