IPhone its older iPhones when issuing operating system upgrades. It has spurred allegations that the firm has been using this as a tactic to prompt users of older iPhones to buy newer models. Up to the iPhone 4, all iPhone models, as well as other iOS devices were manufactured exclusively by Foxconn, based in Taiwan. In 2011, after Tim Cook became CEO of the company, Apple changed its outsourcing strategy, for the first time increasing its supply partners. The iPhone 4s in 2012 was the first model which was manufactured simultaneously by two stand-alone companies: Foxconn as well as Pegatron, also
IPhone 3GS more favorable reviews mainly because it comes pre-installed with iOS 4. Jason Snell of Macworld praised the iPhone 3GS, saying that "the device's internal changes shines in the iOS 4 update, making the iPhone 3GS a worthwhile upgrade compared to its predecessor although a little too late compared to the iPhone 4." TIPB stated that "aside from hardware specific features like FaceTime, Retina Display, and gyroscope support, the bottom line is iPhone 3GS users are getting the same software that makes the iPhone 4 great." Shortly after the release of the iPhone 3GS, some users reported overheating of the device