On our upcoming trip to Greece, we'll have ample access to wifi. Would Skype be a viable mode of phone use in Athens and/or Greek islands?

To call where having what kind of capability on the other end: landline, mobile phone, another skype user, etc?

Google Hangouts will let you call US phone numbers for free while in Greece. If you get a Google Voice phone number ahead of time - if you are from the US, anyway - you can also use that phone number to receive calls via Google Hangouts while in Greece.

You can do the same with Skype but not for free, at least from a regular "phone." Skype to Skype calls from device to device without a phone number are free, though.

With Skype you pay for calling <b>to</b> not <b>from</b> regular phones. The cost is minimal, pennies a minute to numbers in the US. In most of the rest of the world, the cost is higher to call cell phones. You can set up a Skype account with very little money, and there is no expiration date.

You do need a good internet connection to use Skype, especially if you want to do a video call.

You can't receive Skype calls from a phone (phone number) unless you pay for a phone number ($18 USD / 3 months or $60 USD per year). Once you've paid for the number, you can receive unlimited calls (no matter where you are in the world, as long as that country doesn't block Skype) for the duration of the period you've paid for.

If you buy Skype credit, there IS an expiration date unless you use some of it every few months to keep it alive (make one phone call will extend it a few more months). Skype does notify you that you're credit is about to expire, though, so as long as you pay attention to these messages, you won't lose your Skype credit.

Easiest way to do this is to arrange a time by email or text where you will both have a wifi connection, and make your calls then.