When I am traveling around the world and need to call to airlines, credit card companies, financial companies, or businesses back in the US I use SKYPE to make those calls free. I even use them at home instead of my cell phone for those long waits for 1-800 service.

Also, calls home are very cheap and easy to make from a good wifi connection with my iPad compared to using an international phone card from public phones. I don't use the video feature very much, just the audio and most calls come through better than my ATT cell phone unless the wifi is really boggy.