private async void OnBtConnectionStateChangedObservers(Earbuds sendor, BluetoothDevice bluetoothDevice, BluetoothConnectionStatus connectionStatus)
        {
            if (sendor != null)
            {
                bool result;
                result = await sendor.ConnectSpp();

                Log.D($"PairWithMac(): Request to connect Spp with {LocalBtAddress}, result = {result}");

                // FIXME: Retry if failed to connect A2DP over SPP
                for (int i = 0; i < 10; ++i)
                {
                    result = await sendor.SppConnectA2DP(LocalBtAddress);

                    Log.D($"PairWithMac(): Request to connect A2DP with {LocalBtAddress}, try={i}, result = {result}");
                    if (result)
                    {
                        break;
                    }
                }

                sendor.DisconnectSpp();
                Log.D($"PairWithMac(): Request to Disconnect SPP with {LocalBtAddress}");

                sendor.BtConnectionStateChangedObservers -= OnBtConnectionStateChangedObservers;
                sendor.DisableSppConnection();
            }
        }