What are some alternatives?
FireRTC - FireRTC is the easiest way to call from your computer for free
Slack - A messaging app for teams who see through the Earth!
Unfuddle - Unfuddle is a secure, hosted project management solution for software development teams.
GoToMeeting - GoToMeeting is a web conferencing service offering a range of services which are available on Mac, PC, iOS and Android devices.
BobRTC - BobRTC is a VOIP platform dedicated to thwarting telephone fraud, illegal robocallers and scams.
join.me - Instant screen sharing. Instant Aha!