@Nobody @denbesten It is hardly likely that the majority of organisations will be prepared for such an onslaught, let alone Disaster Recovery or BCP at all. An EMP pulse from Nuclear devices, can be widespread, unless you have a collection of Valve type equipment or have formal TEMPEST protected equipment. Then the fallout is likely to be very high indeed. This could turn out to rather like a Supply Chain attack, when one segment goes down, many outages are likely, including "fallout" especially if the Jetstream is conveying the radiated winds towards other parts of the world.
I can remember well into the 80's, protection, and bunkers still exist,. but the majority of these facilities, will now be emptied and relegated to the not in use pile.
We have to assume that, the majority of communications systems would be down including mobile Cellphones systems etc.