Dialpad - Switch is a cloud-based phone system built for Google Apps users.
Video SDK from Zoom - Build fully customizable video-based apps
GlobalMeet Collaboration - From cloud PBX to conference calls and meetings to online events, GlobalMeet is a business communications platform that helps take you where you need to go.
Amazon Chime - Online meetings and video conferencing
Aircall - Aircall is a call center software of a new generation designed for fast growing companies. Setup instantly and integrates to your CRMs
AuthKey.io - SMS API and WhatsApp Business API