Diane, you will only have cell service when you get close to an island that has a tower. Call your provider and see if the islands you are visiting are in your network, if not then you will have to pay roaming charges and they can add up. If you need to be in contact with someone at home your best bet would be e-mail.
There was a topic about this not too long ago, but someone said they called their phone compnay and asked them to turn on the international roaming so that they could use it in other ports. That was for Sprint though, but I am pretty sure there is something similar At&t
I do believe AT&T is one of the companies that the tower on Mariner supports. We had cell coverage the whole time we were on ship(Verizon). Cost depends on your cell company, and most people's plans will have them on roaming on the ship. Call AT&T and ask them.
My carrier is Cingular (now AT&T). Here is what I did: I had them activate International Roaming before going to Bermuda, the intent being that, if I received an SOS call from home via the call going through the ship's switchboard, I would be able to return the call from my cell. The AT&T roaming fee is $1.99/minute. If you use Royal Caribbean's ship tower, their charge is $2.49/minute. I shut my phone completely off while on board and in Bermuda. The few calls I did receive went directly into voice mail. The catch is this: Even if you leave your phone on but don't answer it and let your calls go into voice mail, you will be charged the roaming fee when you call your voice mail box (you are in effect paying for the ring). As soon as I returned, I had AT&T disconnect the feature. Call your carrier. AT&T was VERY helpful and clear on this.
I was amazed to see how many people, particularly the young adults on board, continued to use their cell phones. Man, I don't want to see their bills.
i was on the radiance in march, and my phone worked the entire time, whether in port or at sea, i believe my phone said "cingular at sea" while at sea, and while in port it would have another name whatever the partner carrier was. beware i was in st thomas and was charged around $2 a min. i thought since it was part of u.s. virgin islands it might be covered under my normal plan but it wasnt!
soveriegn of the sea-may 2001
star princess-march 2006 (the best so far)
enchantment of the sea-september 2006
radiance of the sea-march 2007
voyager of the sea-september 2007