RingCentral - RingCentral is the leading provider of cloud-based communications and collaboration solutions for small business and enterprise companies
Ring4 Meeting - Dead simple video conferencing - free, in browser
Dialpad - Switch is a cloud-based phone system built for Google Apps users.
Stork.ai - AI-Based Collaboration for Hybrid Teams. Rich media messaging, advanced video and voice conferencing, auto-transcribing and screen sharing. Serendipitous meetings at the water-cooler with your human and AI teammates.
Aircall - Aircall is a call center software of a new generation designed for fast growing companies. Setup instantly and integrates to your CRMs
openmeet - Account free video conferencing with a rooms component that lets you use VC within a physical meeting room. The server can also be hosted in your own cloud for extra privacy/security.