- User opens app (socket is opened)
- User is prompted to input his phone number
- Application starts
- The user is prompted to call a number
- External phone api provider calls app's url to signal that the user called
- The application updates the associated user session based on the phone number provided by
the external vendor.
- The socket process that is watching for the session change emits the event to the browser
- The app's url used by the external vendor also concludes with a reply so that the user
can hear a message on the phone.