application/ios/CallKitEventHandler.swift

import CallKit

class CallObserver: NSObject, CXCallObserverDelegate {
    
    let callObserver = CXCallObserver()
    
    override init() {
        super.init()
        callObserver.setDelegate(self, queue: nil)
    }
    
    func callObserver(_ callObserver: CXCallObserver, callChanged call: CXCall) {
      if call.hasEnded {
                 print("Call ended")
             } else if call.isOutgoing {
                 print("Outgoing call")
             } else if call.isOnHold {
                 print("Call on hold")
             } else if callObserver.calls.contains(where: { $0.isMuted }) {
                 print("Call muted")
             } else {
                 print("Call status changed")
             }
    }
}