UDID: Your Unique Device Identifier or UDID, is another number unique to your physical device used for identification purposes.Apple or your carrier will often ask for your serial number when providing support for your device, and you'll also need your serial number if you're looking to make a trade in. Serial Number: This is a number unique to your iPhone or iPad that can be used to identify your device.But what are these numbers? Here's a breakdown: At some point in owning an iPhone or iPad, you may have noticed one or more long strings of numbers associated with strange strange names like UDID and IMEI.
