Do you have a smartphone? I used my AT&T iphone in the UK by subscribing to GoogleVoice and Talkatone. I was able to make outbound calls to the US over a wi-fi network by combining these two services (not sure if GV works for Canada). I also signed up for an international roaming plan just in case I wanted to make or receive that "emergency" call when away from the wifi network (which I never had to). I would also suggest buying a chunk of data so you can send an occasional e-mail while away from wi-fi.