"What are some things you shouldn't do during a conference call?" This is an excellent subject to consider, especially before your next conference call.
What is a conference call primarily composed of? Sound. And nothing detracts more from a call than bad sound. To do your part for a good sounding conference call, you can do several things. First, use a landline. Cell phones have come a long way, but you can still tell a difference in quality. Second, make sure you are in a quiet place. The other people on your call don't want to hear the lovely background noise of your local Starbucks.
Lastly – and this is the big one – learn how and when to use your personal mute feature. If you aren't talking much (or at all) go ahead and mute yourself. Even if you are in a quiet place, you never know when the unexpected will happen. Monitor your environment and mute as much as possible. Your fellow participants will appreciate it.
Etiquette is another possible "don't" area. Since most participants are not in the same room, sound will be the primary cause of a social mistake. Don't speak over someone else. Refrain from interrupting. Mute yourself before you cough or sneeze.
Also, remember they can't see you, so be careful not only of what you say, but how you say it. Your content, tone and inflection are all they have to go on.