text: Yes, due to the phone or transmission lines being impacted in the area of the blast.  Due to the nature of the grid system, however, the lines will be 're-routed' around the blast and should have you up in running in no time, that is, of course, if there are no other detonations elsewhere.  \n\nIt is also theoretically speculated that high enough kiloton yields at very high altitudes can have effects on the entire continent.  Since airborne tests were stopped in 1963, only computer simulations and theoretical projections have been made regarding the impact of the EMP.