Zoub:
Yes, the dealers at the show can call in NICS checks on the cell phones. There will be problems, though, due to the massive increase in volume (*every* gun sale now goes thru NICS)... there WILL be periods of no service, and lots of delays due to understaffing at the FBI. We see it at my shop now... it's only gonna get worse with the new regs in place. Not to mention all the extra time dealers are going to have to spend on the phone, rather than with customers making sales. It's lost revenue, plain and simple.
But the people who are *really* gonna get screwed are those who want to buy a handgun w/o a permit. They have to be called in to both NICS and the State, and get "proceeds" from BOTH before the gun can be released. And the State Police aren't going to do checks on weekends anymore, or so I'm told... so all those sales go right out the window at a gun show.