How to use the react-native-callkeep.startCall function in react-native-callkeep

const didReceiveStartCallAction = ({ handle }) => {
    if (!handle) {
      // @TODO: sometime we receive `didReceiveStartCallAction` with handle` undefined`
      return;
    }
    const callUUID = getNewUuid();
    addCall(callUUID, handle);

    log(`[didReceiveStartCallAction] ${callUUID}, number: ${handle}`);

    RNCallKeep.startCall(callUUID, handle, handle);

    BackgroundTimer.setTimeout(() => {
      log(`[setCurrentCallActive] ${format(callUUID)}, number: ${handle}`);
      RNCallKeep.setCurrentCallActive(callUUID);
    }, 1000);
  };

const answerCall = ({ callUUID }) => {
    const number = calls[callUUID];
    log(`[answerCall] ${format(callUUID)}, number: ${number}`);

    RNCallKeep.startCall(callUUID, number, number);

    BackgroundTimer.setTimeout(() => {
      log(`[setCurrentCallActive] ${format(callUUID)}, number: ${number}`);
      RNCallKeep.setCurrentCallActive(callUUID);
    }, 1000);
  };

startOutgoingCall(isVideoCall, displayName, callId) {
        this.callKitUuid = uuid.v4();
        this.withVideo = isVideoCall;
        this.callId = callId;
        RNCallKeep.startCall(this.callKitUuid, displayName, displayName, 'generic', isVideoCall);
    }