Microsoft introduced Reset Protection as a new security measure in Windows Phone 8.1 GDR2, and now you can check the status of your device with a new simple online tool. When Reset Protection is enabled, it prevents others from being able to access your device even if they try a hard reset. The device will be completely useless to anyone else, even if they tried to flash a new ROM.
While this tool is great for protection, it can also lead to headaches in certain situations, such as device trades or sales. Microsoft will now let users input the IMEI or MEID of a device in a new online tool, and it will tell them the status of the device. This will ensure that there are no issues for the new owner before you make the trade or sale.