Upvote:5
This solution may be a basic one, but I've done a fair amount of international travelling and I just bring my unlocked Android Smartphone with me. Whenever I find an internet wifi hotspot at my hotel or at a cafe, I just Skype my friends and family. It's free Skype to Skype or you can pay for a subscription (dirt cheap. I think it's maybe ~$3/month for unlimited calls to landlines and mobile phones).
This is not ideal if you need to call them while you're on the road, in a bus, or in the jungle but I've never had the need to urgently call anyone internationally.