Despite telling Visa we'd be traveling, Kate's card was rejected and disabled when we arrived in Greece. Annoying, but solvable. We just needed to call them. We'd even written down the collect number in case we had a problem. After some failed attempts and conversation with the hotel manager we realized that we had no idea how to call collect from a Greek card-based phone. We did a few searches online and still came up short.
Luckly, I thought of using the Google Voice calling feature.
Google voice calling: It's awesome. We've used it repeatedly since and I recommend it.
The calls go over the internet and work great as long as you have a decent internet connection (we've been using hotel WiFi). Open up gmail, and in chat (without hangouts) there's a little icon of a phone. Click the icon, punch in the number and off you go. It's that easy. Calling to the USA and Canada is free (yes, from anywhere in the world). We've been using it to call family without paying a cent. Calls to other places are extremely cheap. I spent five minutes on the phone with a hotel in Switzerland for ten cents.
We do have a cell phone (more on that later), but it's much pricier to use and the audio quality isn't as good. The improved audio quality is helpful if you're talking to a non-native English speaker.