Your comment contradicts itself. It wasn't always called iOS if it was called iPhone OS "for a very short period of time."

And the period of time was not "very short" by my definition at least.

According to [0]:

> Apple announced iPhone OS 1 at the iPhone keynote on January 9, 2007, and it was released to the public alongside the original iPhone on June 29, 2007. > Apple announced iPhone OS 2 at the iPhone software roadmap keynote in March 2008, and it was released to the public on July 11, 2008 alongside the iPhone 3G. > Apple announced iPhone OS 3 in March 2009, and it was released to the public on June 17, 2009 alongside the iPhone 3GS. > Apple announced iOS 4 in March 2010 and it was released to the public on June 21, 2010 alongside the iPhone 4.

It was called iPhone OS for roughly 3 years. About 25% of the time since the OS was released it was called iPhone OS.

[0] https://en.wikipedia.org/wiki/IOS_version_history#iPhone_OS_...