Because skype only allows 8 people to conference call at once....It doesn't?
Right, apparently they have changed it to 24, which would likely get us by 90% of the time; however, it wouldn't support a bunch of the other features that are important for what we use it for.
I haven't used Teamspeak, but Mumble has this extremely annoying cutoff at the beginning and end of sentences that's put there for some utterly mysterious reason and is impossible to calibrate in any way at all (or rather it is possible to calibrate, but the end result will still be pretty much the same and everyone else will still be speaking in cropped sentences).
After testing with a few other users this morning, we did not have this issue....
Anyway, I like it. And it supports Text to Voice which helps the users without microphones.