It's funny you should mention this. My cousin got married a couple of years ago and the elder who gave the talk told everyone to turn their cell phones off for the ceremony. The night before at the rehersual someone called the elder while he was on stage from the hall as a joke.
When I left the Dubs almost 10 years ago I didn't even own a cell phone. Now I would turn it off if I went into a church. I would probally leave it in the car because I believe they conduct electricty and I might get struck with lightning walking in a church because I'm a heathen.