[trout]

That's the old 'someone forgot to mute the call before accepting another call' trick. That's music on hold.

[eridius]

I was on a conference call once where that happened. It took over 20 minutes to figure out a) who the heck was doing that, and b) how to eject them from the call.

[Swannie]

Oh dear. I've usually identified them in 5-20secs, but it takes another 60 - 90 seconds for the Host to block them :/