How can I use my iPhone to mimic an iPod?
I want to put my iPod music files on my iPhone.
Are there apps that mimic the behavior of an iPod?
Question marked as
Yes, The iPhone has the same Music App as an iPod, and works exactly the same. in that regard.
Read here for how to add music to an iPhone:
Sync your iPhone, iPad, or iPod touch with iTunes on your computer using USB - Apple Support