async function start() {
    logger.info('Starting Free Mobile service');
    username = await gladys.variable.getValue('FREE_MOBILE_USERNAME', serviceId);
    accessToken = await gladys.variable.getValue('FREE_MOBILE_ACCESS_TOKEN', serviceId);

    if (!username || username.length === 0) {
      throw new ServiceNotConfiguredError('No FreeMobile username found. Not starting Free Mobile service');
    }

    if (!accessToken || accessToken.length === 0) {
      throw new ServiceNotConfiguredError('No FreeMobile access_token found. Not starting Free Mobile service');
    }
  }
@public
@description This function starts the FreeMobile service.
@example
gladys.services.free-mobile.start();