When my sister left the country to work abroad, we used to call her because we didn't have a computer (and internet connection), then. So, we purchased phone cards at a local telecommunications office; usually, though, it was my sister who did the calling since getting a phone card there was much easier. She said that it was relatively cheaper, too.
Then my aunt went to live abroad, and since she and my mom were quite close, communication between them never stopped. I remember my aunt calling almost every week and then she and my mom would talk for what seemed like hours! I tell you, those phone cards were really a blessing for them ... until now, whenever my aunt calls, they still talk on the phone for hours! :)