This uses an old iPhone that can fit (width) into a card box. This may seem obvious. I'm not into
caring 2 phones for this quick effect. Not sure why I bought it. Oh well.
Another issue is
I don't think most of your spectators will notice the change of cards to phone - they just don't pay
that much attention. (Unless you point it out). This reduces it to phone from card box.
This may work better for magicians who may pay attention when you show them the cards in the
box.