Flutter show incoming call

I created a video calling application but for the moment, when somebody wants to call a person, the receiver is getting a push notification to start the call. I want to be able to show an incoming call screen, something like WhatsApp does or Facebook. Are there any 3rd party packages you know about and I couldn't find or am I stuck on using APN and Activities?

I tried by now looking on how bridging works but looks like a lot of work and aiI'm not entirely sure I can actually complete it.

What is CallKeep?

React Native CallKeep utilises a brand new iOS 10 framework CallKit and Android ConnectionService to make the life easier for VoIP developers using React Native. For more information about CallKit on iOS, please see Official CallKit Framework Document or Introduction to CallKit by Xamarin.

You can use This package in order to implement a call system.