No. If you're experiencing difficulty in making calls or calls cutting out, check to see if you have all the bars for great coverage where you are. If your signal is strong but you're sounding muffled to someone, simply leave a little space between the covers when you fold them back. This will uncover iPhone's noise-canceling microphone, which is located on the back by the camera lens, clearing up the conversation.
Will BookBook interfere with my wireless signal?