Sherry is correct. Most SIM cards come with an expiration date that has to be reactivated on time. That's why we get a new one each year. There are anecdotals about cards being used each year, but I don't want to get to Aruba and "top-off" someone else's phone number! $20.00 a year gets us a number that lasts at least for our two weeks.
Arubafastphones no longer has a kiosk in the airport so rental would have to be arranged through the website.
My AT&T store didn't know how or didn't want to to unlock my phone, so it isn't always easy to get it done. At&T will send you unlock codes if you request them, but don't mess up. I just bought a phone off the internet for less than $50.00 and use it for Aruba.

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Walt

"Vacation is what you make of it, what you take from it and what you leave behind."