I think it’s confusing because A) you don’t see this screen very often unless you are on the phone a lot with incoming calls and B) two options have the hangup option but they refer to hanging up different calls.

I think this could be improved by changing the text on left option to “Hangup & Accept Incoming.” Change the middle to “Decline Incoming” and so on.

It’s implied of course but multiple buttons having the same hangup symbol with different meanings is part of the reason people struggle with this. That and you encounter it unexpectedly while already focused on a phone conversation so your attention is divided.