Festoon (Score 1)

Thanks everyone for your super-helpful responses. For now, we'll be using Festoon (www.festooninc.com) -- we've already had 14 people on it during a single call from our 4 locations. Once the call is started, it seems to work great. The call initiation is pretty clunky -- you have to start calls using either Google Talk or Skype. -Darren