The Bria app is currently compatible with the Callwise Telephony system, however there are a few tips which are useful and will help you to preserve battery life.
Firstly, when you are setting up the account on Bria, ensure you have the transport "TCP" selected. (the default is usually "UDP").
Once this is done, you can then disable "Run In Background" mode. This is accessed under Preferences > General.
Why disable "Run In Background"?
It seems counter intuitive to disable the Background mode, however this will actually allow Bria to close down and will instruct the iOS operating system to monitor the TCP port for activity. If you receive an inbound call, iOS will instruct Bria to start up again and your call will continue as normal. This is part of the normal iOS VoIP compatibility features.