Free | iTunes Link
For me, Skype has become a well known social app that people can relate to, so I use it as the bar for comparisons. The Skype App could almost always connect even over 3G. However, sometimes it would have been better had it not. It offers low sound quality and does not allow one to connect to SIP Trunks other than Skype, which may be the reason for the sound quality issues. A nice feature that helps users prevent themselves from scaring friends is that you can test your call quality by recording a message and having it played back. As apps go, the setup and interface mimics its PC relation well enough to pass. I wouldn’t want to rely on it for business though.
Overall: Interface C, Sound Quality C, Connection A, Setup C
About the Process
The review of these SIP based iPhone apps for using VoIP was far from scientific. The very unscientific testing was done in 2010 across 3 states (IL,IN,MI). It involved using the app over 3G, joining public Wi-Fi, and secure Wi-Fi connections. When connected, each app was used and rated by its positive and negative qualities. Apps have been chosen based upon positive reviews and ability to connect to any SIP Trunk.
Please read about safe Wi-Fi habits (Free Wi-Fi the World Over) before using these apps on open Wi-Fi.