Okay, SOMEONE at your wedding should have a cell phone on at all times; Aunt Mazie may get lost, your officiant may be a little late (not that this would happen to me….), your wedding cake person may have the wrong address. BUT that being said, your guests, as they are escorted in, should be reminded to turn their phones off. Have your ushers or the banquet manager remind them as the arrive. Do not have your officiant or minister announce this from the ceremony space; it ruins the ceremonial space and trivializes the importance of what will happen there.