Daily.co for Intercom - Free video calls & screen shares embedded in Intercom
Misakey - Send encrypted documents & messages to anyone
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.
Wire - Private & Secure Messenger
CallKite - Your website’s video call center in just one click.
Got A Minute? - Messaging app that limits conversations to 1 minute