It seems like no one (incl google hangouts, msft, etc) has been able to solve the online conf call problem. Maybe it's not solvable? And no, other solutions are terrible too (join.me, ringcentral, etc).
I don't think i've ever been on a Internet-supported conf call where there hasn't been at least one major issue.
My cynical mind tells me the telcos have some custom software/hardware that detects conf call traffic and starts dropping packets but maybe that's just negative thinking[0]...