Mute the conference call

Most of the posts thus far have dealt with in-person meetings. But we all often do meet by conference call these days. And a meeting by phone appears to bring a whole new set of challenges to the art of meeting. First and foremost, I think a conference call that has any kind of presentation element, followed by a question and answer period, has to be automatically muted. I know this must be expensive, but cost must be weighed against the waste of resources associated with a call that is disrupted by background noise, or better yet, the clueless, annoying person who thinks they are muted when they are not (imagine dog barking, intra-office gossip, keyboard clacking, etc.).