We just got back from a short vacation in the US where we did not use our IPhone 4S phone. We ensured Cellular data was off in the US and may have turned something off to even prevent texts, though we don't recall what that would have been. Now that we are home we have "No Service" We have tried Toggling airplane mode on and off again. We have turned Cellular Data on. We have changed carrier to "Automatic", and we have also manually selected Koodo. Still "No Service"