If both parties have the internet then MSN messenger has a Voice Chat function, as do many Instant Message programs. If you are not a fan of IM's, try Ventrillo or Teamspeak.\n\nSkype has already been mentioned.\n\nYou can purchase telephone handsets for your PC if a headset/mic combo is not suitable.
How can I make free - full free- International calls ( from and to countries out of USA)?