Real "cost free" VoIP service is available using voipCheap that allows you to make free calls to both PC's & regular phone lines. voipCheap includes many destinations outside USA and Canada that can be called without paying a cent. A possible downside is the weekly 300 minutes that you can use each week, per IP Address. If you talk more than the included 300, you are required to pay for further calls, you are also required to pay for calls outside of the destinations listed on the free call list.

I don't talk on the phone 300 minutes per month, usually, so this is not  a problem.

voipCheap has a 4 MB download.  Easy install wizard.  To make calls in the U.S., use this format:

19072271234

voipCheap page is here!