Usually, I get a pay-as-you-go SIM card for whatever country I need & swap it for my US SIM. However, this trip is a Road Scholar island cruise. The ship is really more like the hotel because every day, we're on an island, but the wifi will be very slow and cost extra. We depart out of Istanbul, which would require another SIM card. I could get the Greece SIM, but I'd only be able to check email etc while on an island. Altho, since we're not going to be in open ocean but just the Cyclades, maybe I'll be able to data on the boat?

Or, I can rent a TEP hotspot thingy. Supposedly, I can keep my AT&T prepaid data use when connecting to the TEP. I just haven't been able to locate enough info about it, and want to know if anyone here has ever used one.

All advice welcome. Thanks!

Greek cellphone providers, Cosmote, Vodafone GR, etc have excellent coverage in the Cyclades, and you would even get a signal out at sea, at least that’s what I’ve found on ferries. Buy enough data along with a prepaid SIM and you can use it for internet surfing as well as email and texts. If you run out of data you can buy more at most supermarkets on the islands. Your cruise ship will probably have its own wifi as well, and may prefer you to use it while on board.

Most cafes on the islands have their own wifi networks for customers, but they aren’t very secure. Everyone gets to know their passwords, and the signal often carries beyond the premises.

A Mifi also has a SIM. It's just that TEP is including it in the offer. You'll be using whatever network they've bought time on. Which may be limited to save money for TEP.

If OTOH you go with a local SIM you'll pick the package you like and usually get full access to the best speeds the company offers.

No idea what TEP is charging but in the past those tourist MiFi packages have been more expensive than buying your own device and a few months service. You pay a hefty price for the convenience of them bundling everything up

Thanks everyone. I'm glad to know that if I get a Greek SIM card, it will likely work in the Cyclades. I think that's the way I'll go.

Thank you all again for your help. I knew if I came here, I'd get a good answer!

Happy traveling.