Remember to ask your wedding guests to turn off their cell phones. Few people can say that they've never had an awkward moment where it slipped their mind to turn off their ringer and it caused an embarrassment. People are excited to be at your wedding, and between all the small talk about the beautiful flowers and anticipation for the ceremony, they may forget. It is perfectly acceptable to have a small sign by the guest book or in another central place. You can also include it in your program.