Soft Phones
If your PC has speakers and a microphone, you can make phone calls by downloading a soft phone. Or you could replace your microphone with a USB phone, a phone that plugs into your PCs USB port.
Download software phones from SJLabs at http://www.sjlabs.com/sjp.html
There are packages for Telephony providers such as Vonage, VoiceGlo, Free World Dialup, and Stanaphone.
Dante’s DIAX Software phone is small (300kb) and free for Windows from http://www.laser.com/dante/diax/diax.html
Versions of Microsoft Messenger 4.7
Idefisk is a good looking softphone client for IAX2
http://www.asteriskguru.com/tools/idefisk_beta.php
