Skype

Download this VOIP software using peer to peer method. Tested with Eugene who is in Spore and surprisingly the voice quality is quite good. There are no much delay and most important is that it is free. Recommended. Of course this is only good if you have broadband which I am using to test. Not sure if it works well with dialup. Long time ago, I used Net2phone over dial up and the quality is so bad.