HTC Droid Incredible

Has anyone ever had their voice completely changed by this phone? My sister just called me and it freaked me out. She sounded like a man disguising his voice in a horror movie phone call. I know it was her because I asked some questions that only she would know the answer to. This same phone makes random phone calls.

She was going to reboot it and see if that helped. Any suggestions as to what it could be? She is going to try and make it to a store tonight.

Just curious.