As per the title, I'm looking for an App that supports both CallKit and PushKit that can be provisioned with my own SIP provider.
CallKit is the feature that allows you to answer from Lock Screen like a normal call. PushKit allows the calls to come through regardless whether the App is closed / running in the background.
SessionChat is as close as I've come. It supports CallKit but not PushKit.
Groundwire looks as though it might support both but I don't want to pay to trial it.