Skype - Stay in touch with your family and friends for free on Skype. Download Skype today to chat and call on desktop and mobile.
Slack - A messaging app for teams who see through the Earth!
toolani - Cheap international calls
Standuply - Run daily standup meetings and track your metrics in Slack
mytello - Cheap international calls via local dial in number at very attractive prices.
Glide 3 - Lightning fast live video messaging