My wife is travelling to Toronto, Ontario soon, with her unlocked HTC Sensation 4G, and wants the best way to voice-call and text back to me in the U.S. She'll have WiFi access at her hotel. We have the T-Mobile "World Class International Service" added to both phones. The choices appear to be the T-Mobile International roaming (at 59c/min, ), or the Talkatone or Skype for Android apps. For the VOIP options, is Google Voice a necessity for those to work? And, does GV only work in the U.S.? Appreciate the advice, thanks!