Every working day, I spend a good few hours in conference calls with colleagues in the US and Europe. In general, they are not terribly productive as much of the side conversation and nuances of the points are lost to those who can only listen in.
It takes a special skill to chair a conference call and make it productive. In a face-to-face meeting, you can see when someone is thinking through a point or is trying to interject.
I find them frustrating — they’re fine as checkpoints, but not where action is needed and decisions need to be made. Take good notes, circulate the minutes, make sure people know what they’ve gotta do!