Truphone is a free software app for your mobile phone that routes your calls over the Internet. These calls are made using VoIP using your phone’s WiFi connection and even Nokia and Blackberrys can make calls via Truphone’s network without a WiFi conn.
In case you’re wondering what’s in it for Truphone, their business model is to charge lower rates than your mobile provider, particularly for international calls or calls made when you’re roaming abroad.
More info from the manufacturer
Price: Free for software. Call Rates start at $0.06/min.
(Please note prices are subject to change and the listed price is correct to the best of our knowledge at the time of posting)