https://medium.com/@wdmartins/building-a-circuit-communication-device-using-raspberry-pi-716a30bc60a7

This article intends to show the Circuit SDK’s portability and how it can be easily integrated with inexpensive hardware to build all kind of communication devices.

Circuit is a team collaboration software supporting chat, voice, video, screen share and much more. It’s available on the browser, as desktop application, iOS and Android. The free version allows up to 100 users and 3 users per conference call without any feature limitation.