Odds of setting off a primer with a cell phone, pretty darn slim I believe. I would think that a gun shop owner prohibiting cell phones in his shop. Probably doesn't want a customer calling another shop to check on price's. Customer goes in and price's a gun, then calls the local Gander Mtn.,Cabela's,Bass Pro, or just another shop, tries to beat down the shop he's in for a couple bucks. I know of several gun shop owners in my area, that will not set up at gun shows, just for this reason alone. Don't want to hassle with the customer trying to beat them down $10-$20. gypsyman