From Spice i2i:
With S-unno, you can use your iPhone or iPad to 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 2cents/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.