There are so many beautiful UI hints with this.
1) The shape of the microphone positively urges the user to lean forward and talk into it. Compare to a modern smartphone where it's not at all obvious where the microphone is.
2) The giant red button next to the microphone positively scream "press me to talk", and it's obvious that the red LED will light up when the button is pressed. Removes any "is this thing on"? thoughts.
3) The patch panel is quite genius, it's obvious how to target the desired recipient. One might quibble with the plug systenm, but using the large style plugs is a great choice for unsteady hands. These plugs have more leeway if not plugged all the way in than micro style plugs.
4) The recipients are all in a line, and due to the design, one of them is always selected. That removes any "did I select someone", sa I sometimes experience when sharing on my phone to some social network.
5) What's more, the last selected recipient is persistent, even in the event of a power cut.
6) Thermal printer is genius. Yaya can tear off important messages and carry them with her.