When the app is in background event listener endCall does not fire requests until app is re-opened

Bug report

• I've checked the example to reproduce the issue.

• Reproduced on:

• Android

• iOS

Description

When I have my app in the background and I receive VoIP notification and I reject/decline the call, I can see my event listener (endCall) is triggered by my logs, however I have a service API call within this method that should send a request to the server to notify that the call has been rejected.

`RNCallKeep.addEventListener('endCall', (callDetail: any) => {
console.log('endCall is triggered');
RNCallKeep.backToForeground();

const stompService = new StompService(null);
stompService.rejectIncomingCall(callDetail.callUUID);
RNCallKeep.reportEndCallWithUUID(callDetail.callUUID, 2);
});`

My stomp service request is not sent until I manually re-open the app, backToForeground seems to make no difference.

Versions

- Callkeep: 4.3.1
- React Native: 0.64.2
- iOS: 14.7.1
- Phone model: iPhone XS Max

Start with the iOS handling of the endCall event and trace the provided listener's calls to backToForeground, rejectIncomingCall, and reportEndCallWithUUID. Reproduce the backgrounded-call case on iOS and verify that rejectIncomingCall sends its request before the app is reopened.