I just wanted to point out that this is for calling FROM the USA to Jamaica. If you take your AT+T phone to Jamaica and call back to the USA, rates start at $1.69 per minute for calls, text messages are 50 cents to send, picture messages are $1.30 each to send, and data (if you don't think to sign up for one of their special roaming data plans) is .0195 per KB which doesn't sound like much, but there are approximately 1000 KB in a MB so each MB is almost $20... and there are approximately 1000 MB (actual count is 1024) in a GB... each GB of data will cost you a whopping $19500.
Their "special" data packages don't get much better... you can pay $25 up front to get a whopping 20MB and then .005 per MB after, or $60 for 50MB then .005 per MB after.
So what I'm saying is don't be confused, and when you take your AT+T phone out of the country, BE CAREFUL! It can get extremely expensive fast. You can easily use dozens of MB just flipping through your Facebook page, and if you download an email attachment like a picture, they could be huge (100's of MB up to GB's!) and run up insane charges.
If you must use data and texting when in JA, you might want to consider T-Mobile. T-Mobile customers in JA get unlimited texting within JA and back and forth to the USA, as well as unlimited data while there. Calling within JA and back to the USA runs 20 cents per minute... These rates are included in their basic plans, no extra charge, and also allow the same international use in over 100 countries.