When a device is "Out of service," what is its status?

When a device is described as "Out of service," it clearly indicates that the device is not functioning. This status means that the equipment is incapable of performing its intended duties or tasks. When a device is out of service, it is typically unavailable for use until it is repaired or restored to operational condition. This status would prevent any reliance on the device for activities or functions that it is designed to perform, ensuring that personnel understand not to utilize it during this period.

In contrast, the other possibilities suggest varying levels of functionality, which are not applicable when a device is out of service. Being operational, available for use, or in standby mode implies some degree of readiness or functionality, which is clearly not the case with a device that is out of service.