Education has to be the key ... let people know it's not OK to use cell phones or to text during or performance, or for that matter, to photograph or video with those small cameras. At our small community theater, we play a prerecorded message before each production welcoming them to the theater and reminding them to turn off cellphones and that picture taking or videoing is not permitted by copyright law. It works for us, and I hope it can work for others.