Was the original motivation to force a software update? To check for phones that were reported stolen? To collect information about the users?<p>Two explanations that I think are unlikely:<p>First, I don’t think it has anything to do with software piracy since iOS or iPhone OS have always been included for free with the phone. So this is not the same situation as Windows Activation where Microsoft is trying to make sure you paid for the software.<p>Second, I don’t think it’s related to the carrier or cellular provider because you can (at least currently) activate an iPhone without any carrier or even a SIM card so long as you have an Internet connection (through wifi or USB). Besides, if this were about registering a carrier, the iPhone should connect to the carrier’s servers rather than to Apple’s.
> Second, I don’t think it’s related to the carrier or cellular provider<p>Well you thought wrong. iPhone is very much a closed system with a lot of back end secret sauce to make the whole experience "just work". Carriers that officially support the iPhone get API access from Apple but Apple ultimately controls the devices.<p>Things like SIM lock etc. are handled through Apple's servers. The carrier simply makes a request to Apple to unlock the phone.<p>This is also how they enforce MDM for corporate phones. Reset a phone? First thing it does during the mandatory "activation" is check the serial number against any MDM policies to push onto the phone.<p>And so on.