[gsich]

I had this recently with my phone. It was on silent, so ringing wouldn't help. Still connected though.

I then looked at the signal values in my AP. Kicked the phone from one AP, so it would connect to the next. The signal strength was almost the same so I figuered it must be in a room with somewhat equal distance to the APs. I went to that room, no lights on, called and the display turned on.