Apple most likely has a pre-OS firmware that pings a local update server and downloads/flashes the OS when an image is available. That way they don't have a ton

Apple most likely has a pre-OS firmware that pings a local update server and downloads/flashes the OS when an image is available. That way they don't have a ton of iPhones hanging out on the line waiting for GM. I'm not sure how they would test for update failures in that situation. I suppose they could have a LOM or something that validates the software is installed, reports back to the mothership, then deletes itself. That would imply that it's part of Apple's secure chain.