Greece, Italy Sim Card?
 

I have an unlocked cell phone.
I will be in Greece, Italy, and Croatia for a 7 day cruise.
What is the cheapest route to call the USA and receive calls from family?
I would expect 30 minutes of calls for the week.
Any recommendations on what you have done?

You definitely want to make your calls when at port rather than using the ship's tower. A roaming sim that works in all those countries will probably the best. If you home carrier has good roaming rates (if in the EU) that is another option too.

Not necessarily the cheapest but you'd do better getting a country-specific card in Greece, Italy and Croatia if you are going to make short calls.

Greece: http://www.prepaidgsm.net/en/greece.html
Italy: http://www.prepaidgsm.net/en/italy.html
Croatia: http://www.prepaidgsm.net/en/croatia.html

Most mobile operators will give you starter credit of €5 (or equivalent) to start.

International SIMs are a mixed bag. You have the convenience of a single card/number for multiple countries but your per minute rates aren't as good. Another alternative is to "roam" with European cards. Outbound calls are more expensive and you have to be sure that either you have enough credit so that you don't have any way to refill. If you go with a Vodafone affiliate you can get cross-country refills that will work in any country with Voda service (Italy and Greece for instance.)

For 30 minute of at port calls it might be cheaper just to roam or buy a EU roam package from your US carrier than to buy a SIM card for EU (Voda EU SIM was about 18Euros) or individual SIMs.

Do you want to spend your precious vacation time looking to buy a SIM card in each port and then try to load it without English instructions? Then you have to give the number for your callers to call you.

Most cruise ship terminal have international IDD coin (Euro) operated phone which is very cheap for outgoing long distance calls. That is how the ship's crew keep in touch with home on their days off at a port.

try www.iphonetrip.com - they rent sim cards and iphones that allow free internet access overseas and very cheap calls. Besides, if you use iCall with them, you can call the US and Canada for free.