What Asterisk is. Asterisk is an open-source framework for building telephone systems. It implements SIP and other VoIP protocols, bridges calls, runs IVRs, and executes dial plans — the rules that decide what happens when someone dials a number or when a call arrives. In practice it behaves like a private branch exchange (PBX) you host yourself, so you are not tied to a single vendor’s cloud or handset ecosystem.
What I set up at home. I installed Asterisk on a Raspberry Pi 4 with 8 GB RAM, running DietPi — a lightweight Debian-based image that keeps the Pi responsive for a always-on service. Asterisk runs as a normal system service there.
Our cordless handsets sit behind a Gigaset GO Box 100. I configured that base so it registers to my Asterisk as the SIP endpoint the house phones use. Once that link was in place, Asterisk sees the DECT phones as part of the same logical phone system.
From there the interesting part is the dial plan: besides normal calls, I wired extensions and patterns so that certain dials trigger Home Assistant webhooks. HTTP requests from the dial plan reach automations on the home network, so from the same handsets we use for voice we can start or stop scenes — lights, modes, whatever those webhooks are mapped to — without opening an app.
It is a small integration, but it closes the loop between “house phone” and “house automation” in a way that feels natural once the mapping is tuned.