Make a dumb doorbell smart with Shelly 1 - Share your Projects! - Home Assistant Community

Where you already able to connect it? Otherwise you can connect the cables according to how they are connected to your transformer. See this post 34 for more details. You should be able to use the way Rubueno describes the wiring.

Make a dumb doorbell smart with Shelly 1 - #125 by capsel22

dumb -> smart doorbell wiring help!? : r/homeassistant

Make a dumb doorbell smart with Shelly 1 - #100 by arganto - Share

Shelly support group (English Version)

Make a dumb doorbell smart with Shelly 1 - #98 by arganto - Share

GitHub - poweredgenl/smarthome: Smarthome repo with json files

Shelly support group (English Version)

Make a dumb doorbell smart with Shelly 1 - #40 by mr_density

Shelly One WIFI Switch - Scargill's Tech Blog