OpalFone is free software for making international calls at very cheap rates. It supports both PC-to-Phone calls as well as Phone-to-Phone Call. You just activate your account and load money and call to any country at very low rates.
Featuring the industry's lowest rates, amazing clarity and call management tools, mobeefree.com's new Windows PC Application is designed to make inexpensive phone calls easier than ever before. Try it now, for free.
Free VOIP / SIP phone. Use your PC as a phone. Works with any SIP/ VOIP provider/ phone service. Easy to use interface to transfer, forward calls or set-up conference calls. Free download from http://www.3cx.com