I think the system we have here in Australia works well (no idea how it works in the US). Phones allowed in the courthouse, but not in the courtroom.
When I was on a jury a couple of years ago, we had to put our phones in a box before going on to the jury. Once we left the courtroom, we could pick up our phones and use them like normal.
Not even from the smartphone side, but a jury shouldn't have any distractions like that while listening to a trial.