Please pardon my ignorance. This will be our first trip sailing the Grenadines. Most of us have iPhones, which do not have Sim cards. So am I right in thinking that we have to purchase a phone and sim card vs just adding international rate plan for the time that we are away?

I should add- we are all leaving kids at home with grandparents so really want the phone to call home to kids.

Thanks-
Patti