Every cop, security guard and team official in my section at AT&T carries one. Not sure why you'd be surprised they'd have them at MetLife, too.
Give it up already.
LOL, like a garden variety usher's walkie talkie could communicate with the digitally encrypted helmet speaker. If, so we could all listen in on coach to player communications like NASCAR fans. Unless the Giants rigged up a 2ndary receiver in Elli's helmet, I'm not sure how they could have communicated with him via a security guard's walkie talkie.
"The NFL has said there are some 268 million different military-grade encryption codes protecting the frequencies. And while security is strict, teams also do their due diligence to protect transmissions."
http://gizmodo.com/5937115/nfl-helmets-are-finally-using-technology-to-make-things-not-suck
I suspect it was the system hand held unit or something similar to the one in the picture in the "Gizmo" article above. The pictured hand held unit might be the "walkie talkie" that the Giants coaches were using, and if so could be the "practice" system referenced below. That system has no time limit on it and presumably could have be used by the offense and defense after the 15 second mark. There is a lot more to this than a radio shack security guard walkie talkie being used for a few plays, at least from a technical stand point.
"The "system" is actually two systems: one for games and one for practice.
The practice system consists of a receiving unit in the helmets of the players and an interface that allows the coaches -- who use a different system to communicate among themselves -- to communicate with the players.
The game system is similar but much more complex.
NFL rules only allow one player on offense -- the quarterback -- and one player on defense to be able to receive sideline communications.
A coach on the sideline has to press a button to switch from talking to his colleagues to talking to the designated player on the field. GSC's system allows that to happen instantly, whereas there used to be a one- or two-second delay."