Your all iDevices have UDID (Unique Device Identifier) that sets any iPhone, iPad, Apple Watch or Mac apart from other. This number works like a social security number or a serial number that is given to each and every product made by Apple. A common user may not need to know what UDID his Mac, iPhone or iPad has. But for developers and beta testers, it is important to know this number.
We have listed methods to find UDID of Apple Watch, iPhone and Mac in separate information. And the easiest one is to find this number by connecting your iPhone or iPad to iTunes and find UDID from the summary page below your mobile number. Once you click on the serial number of your device, the UDID number of your iPhone or iPad will appear. And if you want to copy the number to paste somewhere, just right-click on the number and you can copy the number.
It sounds like a piece of cake. But what if your iPhone or iPad is locked and still you want to check the UDID of the device?
iTunes will not identify the UDID of a locked or non-activated device; in this situation, there is only apparent way: downgrade your iPhone or iPad to the public release of iOS if you have registered your device to Apple’s iOS Developer Program.
But if you are already using public version of iOS, there is one way to find UDID of your locked device.
How to Find UDID on a Locked iPhone/iPad
Step #1. Connect the iDevice to your Mac.
Step #2. In your Mac, select Apple icon seen at top-left in Menu.
Step #3. Press and hold Option key and click on “System Information”. (By pressing Option key, you can avoid the entry of “About This Mac”)
This will show you a list of Mac's USB ports and other attached USB hubs on the right. You will find your iPhone in this list and check the bottom panel. You can see some numbers and letters mentioned in front of “Serial Number”. Actually, this is your iPhone’s UDID and not the serial number.
Though there are other methods to find UDID of a locked iPhone/iPad, this method is more popular as it is easier & quicker; moreover, any Mac user can employ this method. Users who have sound knowledge of iOS also like to use tools found in Xcode to check UDID of locked iPhones.