Recently found this VOIP app, and so far it has been quite good. Been testing it for a few weeks between two iPods in the same LAN using WiFi.
The only critical problem I am finding is that when an incoming call occurs AND the Zoiper app is active and displayed on the screen, one audio ring plays then the app immediately crashes and thus returns to the homescreen. The app is closed, and the other iPod is still ringing it. It does not matter which screen is active within Zoiper, it always crashes.
In contrast, if the Zoiper app is not active/foreground, the notification bar or button appears asking to answer the call, and it operates as expected. The call can be answered or rejected. Answering works and the sound is as good as possible on an iPod (vs iPhone).
This seems to be a strange issue to me. Why would the app crash when an incoming call comes to the device only when the app is active on the screen.
I am using the most recent version: Zoiper 3.7.2 for iPhone, library a47a93e