BATF has pretty much banned them on the premise that the law defines a handgun as having a grip handle at an acute angle to the barrel. The single shot .22 pen gun got away with this because part of the pen rotated to form a grip, and the gun could not fire without this being done. The cell phone gun has no legally defined grip.
About 15 years ago, near Pgh, PA, police persued a guy fo several miles & when they finally got him stopped, he got out of his car, waving his hands like crazy. He had someting in his hands & the cops thought it was a gun. They ordered the man to drop it & he refused numerous times. He ended up pointing his cell phone at the police & was ultimately shot & killed. There was mass hysteria about the cops shooting an unarmed man & how could they mistake a phone for a gun. Cell phones at that time were a lot larger than now. A member of the PA State Police firearms division, actually concocted a cell phone to fire a single .22 round & still function as a phone. This was presented into evidence of the potential danger which could be assumed by police and the shooting was ruled justified.