I remember when I called home this last visit in January, I used the phone service at Island Internet, from what I figured,the phone calls were under $1.00US a minute. So what it seemed was the longer I talked the price went down per minute,if I am correct a 20 minute call only cost $13.00US.I thought they had made a mistake, but it was not, that is just the way it was.
I have used calling cards before, but sometimes you have to pay a service fee at the hotels and sometimes it is hard to get an AT&T operator.
So, it seems to be a very good deal and now it is my only choice. I hope this helps.