Use phone roaming but not data while international

I will be in the Caribbean (on a cruise) and purchased a cruise talk & text only plan from AT&T. It works on land for the islands that I am going to. How can I turn off data usage (I don’t have a data plan while traveling) but still be able to use my phone to talk and text?

I only see 1 toggle to turn off cellular data but it makes the roaming unavailable automatically.

thanks!