I'm actually travelling to Europe. I was able to make and receive calls with my Iphone 4S before I made the OS 6.1.1 upgrade (through my laptop and Itunes while abroad). Then this message came on the screen all the time "waiting for activation, this may take some time" and no service at all. I will stay in Europe for the next 3 months not coming back to the US before... Anyone knows how to fix this ?