Messages from Beyond?

I returned from my daily pilgrimage to Woolies (bread, milk, peas and corn) to be greeted by the light flashing away on my answering machine.
Typical, thinks I. I'm only gone for fifteen minutes and that's when the world wants me.
I press the play button and wait to hear which of my many devotees desired an audience (mum or one of my kids wanting a lift home). What I hear instead is hold music-a bad synthetic rendition of a lesser know classic. After about ten seconds an unfamiliar male voice cuts the music off with a confused "hello...hello" then the line goes dead.
What's happening here?
Bizzare crossed-line fault or mysterious voice from the other side?
One is more likely but the other far more interesting.