I have an iPhone 5 running iOS 9.3.2. I currently do not have active service on the phone but continue to use it on wifi as basically an iPod. I keep getting a pop-up asking me to update the carrier settings but I am afraid to since the phone does not have service. Will updating the carrier settings cause any problems since it does not have service? I would hate to update and then not be able continue using the phone as I have been. Previous service was with AT&T if that is relevant. The AT&T SIM card is still in the phone as well. Thanks for any help.