"Ghosts" on conference line

We just had an interesting problem. During a conference call people started talking that were not part of the call and wouldn’t respond when we asked them who they were. There wasn’t any prompt that they joined and no prompt they left when it stopped. Other than a random glitch I have no idea how to explain this to the manager who is pissed off about it. Any ideas for how to grasp the details of how this happened through the system. They are basically worried about people hearing about proprietary or internally fire-walled data and I need to insure them that didn’t happen. Thanks for any insight.

A search would bring up a recent topic that was talking about this, you should try the search feature, top right of the screen and looks like a magnifying glass.

I know this was discussed a little while ago, I am also trying to find the topic in question.

The NSA is listening to all your calls. Spooky hey ?