I'm guess it would be in the later 90's. It's a movie about someone trying to tap into a super fast layer of bandwidth that would make wireless communications a million times faster or something. BUT the new layer or frequency is the unopened barrier between the living and the dead so once it became active or online or whatever the dead or spirits or demons start coming through to the real world. So anything that produces or receives a signal like a wi fi network or cell phone the demons or whatever showed up. I remember that it ends with the human race not really winning or stopping it, everyone just moved out of the cities and were staying in tents with the military with no signals around cause without signal the dead or bad what ever they are couldn't get you.

Pulse