Slack - A messaging app for teams who see through the Earth!
Dialpad - Switch is a cloud-based phone system built for Google Apps users.
Telegram - Telegram is a messaging app with a focus on speed and security. It’s superfast, simple and free.
RingCentral - RingCentral is the leading provider of cloud-based communications and collaboration solutions for small business and enterprise companies
Mattermost - Mattermost is an open source alternative to Slack.
Aircall - Aircall is a call center software of a new generation designed for fast growing companies. Setup instantly and integrates to your CRMs