Between Skype, Google Voice, Viber and several smaller players, there are plenty of platform-agnostic services vying to put your voice through their IP (get it?), and now UK carrier O2 is introducing us to its twist on multi-device communication with TU Go. It's like a marriage of the traditional phone service with the idea of making calls on your laptop, or sending messages from your tablet. An evolution of parent company Telefonica's similar
