Daily.co for Intercom - Free video calls & screen shares embedded in Intercom
Skype for Slack - Move your slack discussions to a group skype call
Pluot Communications - Big-screen video conferencing for startups
Aircall Now - Make voice calls inside Intercom Messenger 📞💬
WhatsApp - WhatsApp Messenger: More than 1 billion people in over 180 countries use WhatsApp to stay in touch with friends and family, anytime and anywhere.
Slack - A messaging app for teams who see through the Earth!