Amazon Fire Phone did not silent when I answer a phone call

Which playing youtube video, my Amazon Fire Phone, I click answered but the music audio youtube video did not pause or go silent. I think this is another flaw on Amazon Fire Phone. This should be standard functionality, as like other OS such as Android and IOS have this feature where when playing a video on youtube or music app, if you answer the phone call, the player or audio will go silent or pause. This is by default.

Now I think I know why a lot of tech people don’t recommend this phone, but if you want it because of the cheap price, then get it unlocked, that way you can unlock and then install CM11 (Cyanogen Mod 11) with the latest Android operating system, this way you can use any android apps and off course android functionality.