Yes, $6.99 a minute is accurate, but depending on your cell phone company, you may not need it.
I have Cingular, and so far I've been able to use my phone in San Juan, St. Maartan, St. Thomas, Antigua, Nassau, Ocho Rios and Grand Cayman. It did not work in Barbados, Cozumel or Belize.
And of course, when you are on the open sea it will not work. except one day when I saw a small boat on the ocean I figured land was close by and it did work for about 30 minutes until we were out of range.
In both Ocho Rios and Grand Cayman, I know that those with T-Mobile were bothered that their phones did not work while mine did.
If you have a national plan, you may want to check and see where yours will work. Sure saves a lot of money. I've never used the phone in my cabin except to call stateroom to stateroom.