CounterPath’s softphone for iPhone, iPod Touch and iPad allows you to make calls through WiFi or 3G, using your VoipNow account. You can download the softphone from the iTunes website.
System requirements: iPhone 3GS or 4 running iOS 4.0 or later, iPod Touch (3rd Generation or later). It’s not recommended to use Bria on iPhone 3G, iPod 2nd generation or older devices.
The first thing you should do is to start Bria from your device’s menu.