Many believe this to be the most likely massive disaster event. Some believe it inevitable.
Way back before telephones were part of everyday life, much less mobile phones. The primary form of long distance communication that spanned the country was the telegraph, and it did not fair well against a solar storm.
On a summer day in 1859, a silent surge of power from a major geomagnetic storm fueled by a solar eruption hit telegraph offices around the world. Some telegraph operators got electric shocks. Papers caught fire. And perhaps most amazing, many telegraph systems still sent and received signals even after operators disconnected batteries.