
The labeling scheme is also different on the CDMA iPhone 4 built for Verizon, and on the new iPhone 4S. On the iPhone 3G and iPhone 3GS, the letter K may refer to 16GB of storage as opposed to the letter S. However, some older iPhones employ a slightly different labeling scheme, according to OS X Daily. A4 means it’s a black iPhone 4, while the S suggests it packs 16GB of storage.

So if your serial number was 79049XXXA4S, the first to number would indicate it was assembled in factory 79 - presumably a Foxconn factory, which assembles all of Apple’s iPhones - in 2010 during week 49.

It has no meaning other than the order that the device came off the assembly line. If your device is connected to iTunes on your computer, you’ll also see it on the Summary page. A: It is simply the number assigned to your device as it is manufactured in succession with all other similar devices. You can find your serial number either on your iPhone’s box, or in the About menu within the Settings app.
