When I was on my cruise docked in Nassau, my cellphone was completly useless (except maybe for a paperweight). But that was two years ago, and since then, At&T Wireless became Cingular.
However, when I went into the Festival Bay Building (the building people go through to leave the dock (Prince George's Wharf) and enter Nassau) I discovered they sold phone cards in a window (which looked like those large windows in a drive through bank). These phone cards sold for $5,$10, and $20. They workded on the pay phones nearby that window. With that phone card I purchased for $5 and used on the nearby payphone, it costed me only 51 cents per minute to call home. That was sooooo much less than what they charged onboard the ship.