Here's a hint: the problem is between chair and receiver.
Bruce Schneier linked today to this excellent essay on the unseen dangers of mobile phones:
About four seats away is a gentleman (on this occasion pronounced 'fool') with a BlackBerry mobile device and a very loud voice. He is obviously intent on selling a customer something and is briefing his team. It seems he is the leader as he defines the strategy and assigns each of his unseen team with specific tasks and roles.
Eventually, he starts to close down the conversation. Relief might be here at last! Oh no, he goes on to announce the conference number and the pass code - and say he will see them all on the conference call in a minute.