AVFoundation- .audioDeviceInUseByAnotherClient runs after CXCallObserver call.hasEnded (call disconnection) is called - ios

Question

I'm using AVFoundation for video recording. I also use the CXCallObserverDelegate to listen to when a phone call is disconnected.
I go to the background
I make a phone call
While the phone call is active I bring the app back to the foreground and press the button to modally present the vc that contains AVFoundation
Once the vc is on scene and because I'm currently on a phone call the .audioDeviceInUseByAnotherClient gets called and I stop the capture session
Once the phone call is disconnected then CXCallObserver call.hasEnded is called and I restart the capture session. The .sessionInterruptionEnded also gets called but this isn't causing the issue.
This is where the problem occurs. Once call.hasEnded is called then .audioDeviceInUseByAnotherClient gets called again. Since the code to stop the capture session is in there this results in capture session stopping again
In step 6 why does .audioDeviceInUseByAnotherClient get called again after the call has been disconnected?
func sessionWasInterrupted(notification: NSNotification) {
let reasonIntegerValue = userInfoValue.integerValue,
let reason = AVCaptureSession.InterruptionReason(rawValue: reasonIntegerValue) {
case .audioDeviceInUseByAnotherClient:
stopCaptureSession()
}
}
}
func sessionInterruptionEnded(notification: NSNotification) {
print("-----Capture session interruption ended")
restartCaptureSession()
}
func callObserver(_ callObserver: CXCallObserver, callChanged call: CXCall) {
if call.hasEnded == true {
print("\nCXCallState :Disconnected")
restartCaptureSession()
}
if call.hasConnected == true && call.hasEnded == false {
print("\nCXCallState : Connected")
// *** THIS NEVER GETS CALLED IN THIS SCENARIO ***
}
}
fileprivate func stopCaptureSession() {
if captureSession.isRunning {
DispatchQueue.global(qos: .background).async { [weak self] in
DispatchQueue.main.sync {
self?.captureSession.stopRunning()
}
DispatchQueue.main.async {
self?.previewLayer?.removeFromSuperlayer()
self?.previewLayer = nil
}
}
}
}
func restartCaptureSession() {
if !captureSession.isRunning {
DispatchQueue.global(qos: .background).async { [weak self] in
DispatchQueue.main.sync {
self?.captureSession.startRunning()
}
DispatchQueue.main.asyncAfter(deadline: .now() + 1.5) {
if let safeSelf = self {
if safeSelf.previewLayer == nil {
self?.previewLayer = AVCaptureVideoPreviewLayer(session: self!.captureSession)
self?.previewLayer?.videoGravity = AVLayerVideoGravity.resizeAspectFill
guard let previewLayer = self?.previewLayer else { return }
previewLayer.frame = self!.containerViewForPreviewLayer.bounds
self?.containerViewForPreviewLayer.layer.insertSublayer(previewLayer, at: 0)
}
}
}
}
}
}