It can be seen that the war between phone OSs (operating system) is so tough that there are only two biggest dominants: iOS and Android. There are several other systems namely Windows phone, Blackberry OS but the segment is converging to the two giants (hyperlink). OS operators are focusing on how to develop their system to make it more appealing and convenient for users. This fact indicates that beside the phone itself, the OS it contains is the reason attracting consumers.
Despite that there are only two dominating OSs, there are a lot of devices live on them. Apple has the iPhone, iPod, iPad or iWatch while Android-based devices are numerous. Therefore, it can be said that the devices are made and improved in order to help users to make best use of the operating system. In this way, the phone is the medium of the medium (the OS).
Check my Prezi map for my further arguments.