We don't use web conferencing that much. Don't do many sales calls and so forth, but we do have lots and lots of audio conference calls. We use "Intercall Reservationless Plus":http://www.intercall.com/services/audio-conferencing/ and the sound quality is good, but interesting to see how expensive things are and what the quality is. Here are some alternatives as there seems to be nothing I can find like a review of these things on the Internet:
http://www.freeaudioconferencing.com/ seems to be the top hit on Google. I don't understand their revenue model, but they have free audio conferencing services. The main thing is that it does sound like it is in essence a site harvesting your name and phone number tfor telemarketing.