Griffin has had several different version of a doorbell for his room over the years. The previous version used 22 AWG 4-strand wire, running down the hall, over the railing, and down the stairs. It was perfect for Mom & Dad to call him to dinner or wake him up for breakfast without having to yell up the stairs. It's not as elaborate as an intercom system, and not as modern or expensive as families sending texts to each other, but Griffin built it all by himself and it works perfectly.
The newest modification that he added to the doorbell system was to send the signals through the CAT5e wires that were not being used in the house. Mom and Dad added them at the time the house was being built, but that was before WiFi became standard. Griffin's disclaimer- make sure you don't plug in actual network devices while using it for the doorbell system because it could damage the devices since it doesn't use standard Ethernet protocols.
On the downstairs end, Griffin added a pushbutton with a wall plate that matches the others in the house. This hides the wires and make it blend in with the other plugs and switch plates in the house. Behind the plate, he has tucked in extra wires and a beeper so that it works both ways. The beeper is still plenty loud downstairs even though it is covered up by the switch plate. When Mom or Dad press the button to ring his doorbell, he can respond by pressing the button on his end to acknowledge that he heard it.
Upstairs, the system gets power from a plug on the wall, and has a connector for the other end of the CAT5e wire. There wasn't enough space at the wall plate for the wires and beeper and it was hard to reach, so he added a longer wire that passes through yellow plastic tubing, and mounted a round button on the end to make it easier to reach. Griffin and Mom get a "kick" out of pressing the buttons with their feet.