A friend just told me about VIBER for making "free" international calls. I'm reading about it now. Have yet to download Skype or Viber for iPhone 4S. I do have Skype on my MBA. Do these iPhone apps function in the same manner as they do for computers? Is one preferred over the other? Can I use my current Skype account on my MBA when I download the app on my iPhone 4S. Thanks for any recommendations, suggestions, and experiences you can share on these apps.