is practice during a TO a T??

[cmathews]

Coach for A calls TO. Partner blows whistle, A1 has the ball, as partner goes to administer the TO A1 takes a dribble or two then shoots a three pointer. I called a T and we adminstered it. My thought was we are supposed to prevent practice during a dead ball other than half and pregame. In my mind it was clear that it was a T, but upon looking for rules support, I am not quite sure. I have had kids shoot the ball just after a whistle before, but this was a looooong delay. Not that it matters but his team was up 30 at the time... What says the board???