Look at P1 and P2, that is, the prototypes before the iPhone (video)
When, in 2007, Steve Jobs introduced the iPhone, which stood out to be a mix of phone, iPhone and the device, for connection to the internet, he showed a slide of a fake device that looked very much like an iPod, but with a disk controller similar to that of the old fixed-line phones instead of the selector switch the circular of the popular music player of the apple. It was obviously a joke and the audience laughed out loud before to discover the true appearance of the first, historical iPhone.
What the journalists in the room could not know (and that until now did not even know the most of us) is that for the first prototypes of the iPhone, there was really who he had thought a user experience similar (though, of course, without the disk controller).
Those that you can see in the video at the bottom, in fact, are P1 and P2, the earliest prototypes of the iPhone, when it's still Apple we talked about the various possibilities of the graphical interface.
P1 (to the right in the image at the top, to the left in the video) was the prototype edited by Tony Fadell, who had already directed the development group for iPod & Special Projects, while P2 was the variant, curated by Scott Forstall, who had worked with Jobs since the days of NeXT.
As you can tell easily from the video, the P1 was substantially the same as the operating system of the iPod, but adapted to a touch interface, while P2 was an OS completely new (and this is the reason for the slow boot time), which is based on large buttons and easily accessible with a touch.
Remember that the iPod were extremely popular at the time and the people were accustomed to interact with your Apple devices via the selector circular; however, Jobs chose a system developed by the team of Forstall.
Today, this choice is obvious (who ever would like to get to read the tiny lettering on the screen and miss half the display for a controller touch so inconvenient?) but just to contextualize this fight to the epocaper understand the importance of studies on graphical user interfaces and the user experience, and how these two factors have played a crucial role for the success of the iPhone.