See it in action here:
This app is adapted from https://github.com/SophieDeBenedetto/action-cable-example
See Sophie's blog post for details of Action Cable: https://blog.heroku.com/archives/2016/5/9/real_time_rails_implementing_websockets_in_rails_5_with_action_cable
This example uses Delfos for call site logging and Rails 5's action cable for pushing live updates of call sites to another browser.
For this to work from the terminal too (or any other Rails instance) you need to follow the instructions for getting started with redis.