Bria Mobile is an excellent app for your Apple iPhone that can be used with Irish VoIP to make and receive calls. iOS does not allow apps to keep a network connection open in the background so this means that special techniques are needed to be able to receive calls.
The recommended method is to use a silent push message to wake the app when a call is incoming. Bria implement this very effectively by registering through their servers to providers like Irish VoIP. When a call is inbound their server will receive the notification and send the push message to the app to wake it.
See below for a screenshot with the recommended settings for the app. Note in particular the Push Service section as this is key. Other settings can be left as default - just replace the numbers with your number (Username must be in full number format like 353XXXXXXXX) and enter your password.
We have now retired our iOS app in favour of the Bria Mobile app. Download the Bria Mobile app here