A self-hosted app utilizing Twilio to manage and direct calls from the enterphone to each of our phones. As an added bonus, it also trigger Philips Hue lights in our apartment to flash when a buzz is incoming. When a visitor dials your unit on the enterphone, the call will go out to the Twilio service, and will connect to the app running on your server. When the app receives a valid request originating from the Apartment Enterphone number, it will drop that call into a conference room (with hold music) while it then initiates calls out to the two tenants.

When a call one tenant is answered, the call to the other tenant is terminated, and the answered call gets dropped into the same conference room, beginning the conference. You can then speak to the visitor, and key presses get passed through to the enterphone system for remote unlocking of the door.