Ooma's iPhone App Offloads AT&T Voice Minutes

Ooma, which offers residential voice service in the U.S. using a freemium model, released an iPhone app that
lets Ooma customers make domestic and international calls over any Wi-Fi or 3G network while tapping into their Ooma account rather than using AT&T voice minutes. Ooma leverages its own "PureVoice" codec to reduce bandwidth usage by 60%. For international calls, Ooma calculates this will save customers up to 90%.
http://www.ooma.com