/**
 * Called when message is received.
 *
 * @param remoteMessage Object representing the message received from Firebase Cloud Messaging.
 */
@Override
public void onMessageReceived(RemoteMessage remoteMessage) {
    Log.d(TAG, "Received onMessageReceived()");
    Log.d(TAG, "Bundle data: " + remoteMessage.getData());
    Log.d(TAG, "From: " + remoteMessage.getFrom());

    // Check if message contains a data payload.
    if (remoteMessage.getData().size() > 0) {
        boolean valid = Voice.handleMessage(this, remoteMessage.getData(), new MessageListener() {
            @Override
            public void onCallInvite(@NonNull CallInvite callInvite) {
                final int notificationId = (int) System.currentTimeMillis();
                handleInvite(callInvite, notificationId);
            }

            @Override
            public void onCancelledCallInvite(@NonNull CancelledCallInvite cancelledCallInvite, @Nullable CallException callException) {
                handleCanceledCallInvite(cancelledCallInvite);
            }
        });

        if (!valid) {
            Log.e(TAG, "The message was not a valid Twilio Voice SDK payload: " +
                    remoteMessage.getData());
        }
    }
}