the author of this app says:
With S-unno, you can make phone calls to any fixed or mobile number in more than 200 countries at absolutely low rates. Rates start from as low as US 1cents/minute. S-unno uses your 3G or WiFi connection to place these calls so that you can start saving now.
Download is Free, Sign-up is Free! Remember NO subscriptions either!
Not just phone calls, S-unno offers much more SMS, Value-added Services and an extensive list of features, which are up and coming, are available to you at no additional subscription charges.
S-unno is available for PCs too use your S-unno account to make calls from PC or your mobile phone. Calls between S-unno users are Free wherever you are. Get your friends on S-unno and start making free calls!
Features: - Unlimited FREE calls between S-unno users anywhere in the world - Supports 3G and WiFi - Easy to use user-interface call directly from your mobiles phonebook - Call log check out your missed and dialed calls - Advance features: Caller ID, Call Hold & Call Forwarding - SMS offered at amazingly low rates - Easy access to value-added services - To save even more enable the Call Intercept mode, your phone will start using S-unno for all your calls no more worries about using up your mobile minutes
For more information, visit: http://www.s-unno.com