Calling cards are some of the most commonly used option when it comes to calling abroad. They can be used by you or your family back home to call landlines and mobiles at really low rates. For example, calling the United States from Japan can go as low as 3¢ per minute. EnjoyPrepaid.com has an offer giving new customers a free phone card worth 15 minutes if you act now.
Skype is one of my main tools when it comes to calling another computer. The quality is okay most of the time but I found that when calling mobiles and landlines, the rates are a bit higher than the previous option. Still, if you're looking for PC-to-PC voice calls, Skype is the way to.
Your phone is another option for calling abroad, even though it can get pretty expensive. To make sure you won't get charged by the hour for calling a few minutes, check with your provider to see if there are any options for calling abroad. If you’re calling your family regularly, you could pay a small subscription fee for getting lower international rates.