I think there may be some kind of signaling, and that was the reason for the decision to move CNN's front row seat to the back.
Say, for example, in a classified session there's discussion about strategy where POTUS disagrees with the 'experts', but decides to go along with the experts for now in the briefing. Signalling would be a way to tell the press POTUS's actual position so that it could be undermined beforehand in MSM reports.
Could also be something like a bluetooth file transfer. I'm not sure if they are throttled or monitored in the press room to limit efective distance.