An email, even if it goes to a mailing list, differs from a public web page by being addressed. A video conferencing session differs from a video at some home page by being addressed. Machines, including chatbots, can read and write e-mail, but they might be too dumb to qualify as entities. A really capable AI based chatbot that passes the Turing test without mimicking a mentally disabled or dumb person is an entity.

• bitmessage.org
  
• BRIAR(repository)
  
• CoyIM
• Jitsi
• Ricochet
  
• Ring(ring.cx) / Jami videoconferencing software
• Vuvuzela
  
• Serval is a cellphone based mesh network project with its own mobile applications.
  
• Tok/InsightIM(GitHub repository)
• Tox