[iamdave]

Even phone confernces (using VOIP conference providers) have awful quality.

VoIP, especially multi-tenant voip like conferencing is 70% dependent on YOUR local network connection and 30% the provider's infrastructure. Having a high bandwidth pipe is no guarantee for 100% clear and jitterless voip communication. Have you had a network engineer take a deep inspection of voip traffic to see if there's any QoS or packet filtering going on that could degrade performance (i.e. if you're a small office that has your voice traffic occurring side by side with literally every other network device you're GOING to have a bad time).