A method of operating a user device includes: receiving a command from a user to power on the user device, wherein the user device includes information on a restricted zone associated with the user device; detecting, by a monitoring entity of the user device without involvement of any device external to the user device, whether the user device is located within the restricted zone in response to the user device being powered on and before an operating system of the user device is executed; and granting access of the user to the user device by the monitoring entity in response to detecting the user device as being within the restricted zone.