Sign up for google voice, then grab Grooveip from the market, I think you may need an application specific password if you use 2 step authentication with google, but it works great..I was even in the Bahamas last week, and don't think gvoice is supposed to work from international locations but it worked flawlessly over free wifi. For some reason the app was removed from the market a few Weeks ago, but its back now...I just checked.