I'm not convinced there is something to some special radiation for phones on a certain date or hour, especially if they announce it. If they want to beam some weird signals, they tell nobody, and they do it from the more powerful antennas that are everywhere.
It looks more like a distraction, a psychological test to assess the public's reaction, or a data collection operation (they probably know who received the message, and who has chosen no to), or at the minimum condition the population to a state of constant fear and dependence on the government for safety.