IPhone 4 models. In fall 2010, pentalobe screws started to replace the Philips screws used in post-repair units in the US and in production units in Japan. The iPhone 4 shipped with iOS 4, which was the newest version of Apple's iOS mobile operating system at the time. iOS 4 introduced a multitasking system, allowing apps to remain "suspended" in memory, perform certain operations in the background, and allowing users to switch between apps using an on-screen menu. It also introduced FaceTime, which allows users to perform video calls between other iPhone, iPad, iPod Touch, and OS X users. The iPhone 4
IPhone (1st generation) the phone." Jobs introduced the iPhone as a combination of three devices: a "widescreen iPod with touch controls"; a "revolutionary mobile phone"; and a "breakthrough Internet communicator". Six weeks before the iPhone was to be released, the plastic screen was replaced with a glass one, after Jobs was upset that the screen of the prototype he was carrying in his pocket had been scratched by his keys. The quick switch led to a bidding process for a manufacturing contractor that was won by Foxconn, which had just opened up a new wing of its Shenzhen factory complex specifically for this