BLE Advertising on Background

Question

I´m working on a android app of inside of a Contact tracing project. What i need right now is make a background process (idk if, service, foreground service, worker, etc), that can keep the BLE advertiser sending beacons even if the application closes. Is working without issues on the main thread but when i try to convert in a service, it can´t start. This is the service class that i tried:

public class AdvertiserService extends Service {
    private  BluetoothLeAdvertiser advertiser;
    private  AdvertiseSettings settings;
    private  AdvertiseCallback callback;

  @Override
  public void onCreate() {
      super.onCreate();
      advertiser = BluetoothAdapter.getDefaultAdapter().getBluetoothLeAdvertiser();

      settings = new AdvertiseSettings.Builder()
              .setAdvertiseMode(AdvertiseSettings.ADVERTISE_MODE_LOW_LATENCY)
              .setConnectable(false)
              .setTxPowerLevel(AdvertiseSettings.ADVERTISE_TX_POWER_HIGH)
              .setTimeout(0)
              .build();

      callback = new AdvertiseCallback() {
          @Override
          public void onStartSuccess(AdvertiseSettings settingsInEffect) {
              super.onStartSuccess(settingsInEffect);
          }

          @Override
          public void onStartFailure(int errorCode) {
              super.onStartFailure(errorCode);
          }
      };
 }

  @Override
  public int onStartCommand(Intent intent, int flags, int startId) {
     long userId = 
Long.parseLong(PreferenceManager.getDefaultSharedPreferences(this)
              .getString(getString(R.string.user_id_pref_key), "0"));
      MeetingBeacon beacon = new MeetingBeacon(userId, userId);
      Log.d("MEETING_BACON", beacon.getBeaconUUID().toString() );
      AdvertiseData data = new AdvertiseData.Builder()
              .addServiceData(beacon.getBeaconUUID(), beacon.getBeaconData())
              .build();
      advertiser.startAdvertising(settings, data, callback);
     return START_STICKY;
  }

  @Override
  public void onDestroy(){
      Log.d("ADVER-Sv","Automate service destroyed...");
      advertiser.stopAdvertising(callback);
      super.onDestroy();
  }

  @Override
  public IBinder onBind(Intent intent) {
      return null;
  }


  @Override
  public boolean stopService(Intent name) {
      Log.d("SCAN-Sv","Automate service stop...");
      advertiser.stopAdvertising(callback);
      stopSelf();
      return super.stopService(name);
 }
}

And i´m starting this service from main thread as:

advertiserService = new Intent(this, AdvertiserService.class);

    if(advertiserEnabled) {
        ComponentName ret = startService(advertiserService);
        if(ret != null){
            Log.d("SERVICE:", sv.toString());
        }
        Log.d("SERVICE ", "fail");
    }

But ret is always null , so the service cannot start. Idk if using service is the better solution in this case. Anyone can suggest which could be the better solution to solve this problem?