A number of years ago I had a phone ringing nightmare that went even further. I dreamt that the phone woke me in the middle of night. I couldn't reach the phone, so the answering machine picked up. It was one of my friends calling in tears to tell me she'd been raped. She finished the call, and at that point I woke up so alarmed and disoriented that I didn't even realize it was a dream. It was sometime around three in the morning and I very nearly "called her back." The only reason I didn't, was that I look at the answering machine before calling and realized there were no messages on the machine.

So yeah, phone ringing dreams are scary. And so are dreams where a voice says your name.