The only times I've ever had to sign for a package was with Fedex. Every single time I've had something delivered Fedex, a signature was needed. That's how it was for my MacBook and everything else. Since it's being shipped via Fedex for the iPhone, I can only assume that a signature will be required. Which means I'll have to conscript a household member into staying home and signing... hmmm....
UPS-those guys are magic, by the time you're at the door, they've disappeared. I've literally stood like 10 feet away from the door when they've rung the bell, went to the door to open it, and they were gone. Skills.