I'm with @Cfox815. I think it's a lawyer thing because most of the people I talk to professionally respond the same was as well (and obviously the people who call me personally know my voice). I usually answer my business line "Michelle LastName" anyway.
If it's a number I don't recognize I will usually pick up and say, "April speaking" instead of Hello. If I answered saying Hello, then they ask for me, I reply "this is she."
Re: How do you answer...
I'd probably say 'this is (first name)' or 'speaking'