I have t-mobile and service worked ok in the Bahamas, but not at all in Bermuda.
Nancy, do you have a tri-mode (GSM) phone with international service activated? I've not been back to Bermuda since I got my phone but my T-mobile phone has worked for me all over the Caribbean, Europe, Asia, Africa, the Middle East and India.
In checking my coverage on the T-mobile website, if I were there, calls in and out of Bermuda would cost me $1.49/minute. Additionally, GPRS coverage is also available.
MM - I'm checking the Cingular website but have not yet been able to determine if they have coverage there or not but as you can see, even if they do, not all phones/services are created equal.