I am learning here! You use a Mifi. After reading your last message I was thinking of buying an unlocked iPhone and use that as a wifi-hotspot - I could do that and there would be no need for an additional Mifi, right?
Unfortunately, I will have to wait before I can chat with my daughter; she just turned two. I currently work most of the time in South Africa, and I love the google talkatone app to keep in touch with friends - it enables me to call and text with any US number for free and chat on gmail.