XMPP too. It can do video calling: https://xmpp.org/about/technology-overview.html https://xmpp.org/about/technology-overview.html Sad that Google + Facebook p

XMPP too. It can do video calling: https://xmpp.org/about/technology-overview.html https://xmpp.org/about/technology-overview.html Sad that Google + Facebook pulled out of federation a long time ago. We could have had bring-your-own-client cross-network all of this stuff. We still can, but realistically we won't.