Urgent Overhaul of Outdated Project for CallKit Support

[erwiower2]

Describe the bug

Hello, we are now in 2025, and there is no official app that does not support CallKit. The .cpp and .hpp files in the project are outdated and should no longer be supported. Please overhaul the entire project in the next release, as there are still issues where, with CallKit, no sound is heard during a second call, and the second call gets terminated. The project is supposed to be designed for iOS but provides 0% support for Apple's CallKit logic. As it stands, this is not a VoIP app but a cobbled-together project!

I don't want to have to edit all the CPP and HPP files myself; it should already be programmed. Otherwise, there's no point in providing a pre-made project if I have to revise all the functions myself.

Steps to reproduce

Use this app with CallKit and you will see.