So while I believe Mobile Voip is eventually how all calls will be made in the future, the real challenge will be how to integrate the applications that will be compelling to the general public. Nearly 100 million users are expected to be using mobile VoIP by 2012. With over 471 billion calls likely to be made via mobile VoIP by 2015 !! Of course the cost for mobile voip calling international rates is the real “killer app” right now, but that will change over time to more sophisticated services. In fact, while I was in a clients office, and mentioned that Truphone has really just leveled the playing field by recently reducing most of the rates to major countries, our client was wowed in finding out that his best deal was not even close to what Truphone http://www.truphone.com/ was offering for calls into Turkey on his Iphone at $.03/min. With voice, IM, conferencing, video and other features, this space has a high probability of becoming a breakout sector to watch as the mobile traffic starts to migrate onto Wifi and 3G/4G data networks. It will be interesting to watch how the big guys like Google, Apple and other forces will factor in determining the faith of how call flow (and cash flow) will end up traveling.