I made a phone call, got voice mail, and tried to hang up. Before I could hang up, the person called me back, so I talked to that person. After the person hung up, I saw that the first call I made was on "hold", so I switched to it, and tried to hang up. But the phone would not hang up. Noting I did would end the phone call. I could use the dial pad, I could go to the home screen, but the phone call would not end. I held the "end" button down and nothing happened, and I couldn't get out of the phone call. So I finally popped the battery cover, and pulled the battery to reset the phone. Very strange, hope it doesn't happen again. But overall minor annoyance and not a big dea.