Bahamas for a week

Assuming that you're on a current postpaid plan, there should be no problems. If you're going on a cruise ship, be aware that roaming rates onboard the ship are much higher than on dry land. Here’s the rate page for Bahamas. https://www.t-mobile.com/coverage/roaming?country=Bahamas

Read this document https://www.t-mobile.com/support/coverage/international-roaming-services