If you have an iPod Touch, then here's a way by which you can use that as a free phone thanks to a new iPod Touch application called Truphone.
The Truphone application is free for use. Once you install this app on your iPod Touch, and with the addition of microphone adaptor you can make free calls - no matter where they are in the world, to other iPod touch owners, to customers of Truphone’s Internet telephony service, and to users of the Google Talk instant messaging service.
Features...
