That rings a bell

I was sitting in my office today when the phone rang. So I picked it up and answered it. But it continued to ring. I pressed a few buttons on it and was mildly annoyed to hear the dialing tone. I seem to have an office phone which is both ringing and also giving me the dial tone. Most mysterious.

I was just trying to wrap my head around this concept when the ringing stopped. Thank goodness. I picked up my mobile phone and glanced at the display out of idle curiosity. I seemed to have missed a call recently. Interesting. I'm sure I would have heard it ring.......

I'm blaming jetlag for this. That and the fact I've got new mobile and office phones recently.