[H3g3m0n]

I could see it being potentially being much worse. Some could buy a phone for every tower, set them up to wait for a trigger call that when received will cause then block every call in the country simultaneously. There are probably close to 200k towers in America so it would be fairly expensive and unlikely to get that many devices into place. Then again someone could just target the top 5 populated cities or if they coordinate it with a terrorist attack or if they are smart enough to know what the stock market would do...