What are some alternatives?
Slack - A messaging app for teams who see through the Earth!
join.me - Instant screen sharing. Instant Aha!
Mattermost - Mattermost is an open source alternative to Slack.
GoToMeeting - GoToMeeting is a web conferencing service offering a range of services which are available on Mac, PC, iOS and Android devices.
Riot.im - Open source interoperable collaboration app.