My doorbell button and chime are connected to a 8V transformer. Make sure to set the bridge on the Shelly to 12V DC. Check the manual on how to do this. You have to strip the wires from the adapter in order to connect these to the Shelly 1.
Shelly® may work standalone, without being managed by a Kigurumi home automation controller, in the local WiFi network, as well as through a cloud service, from everywhere the User has Internet access. Shelly® has an integrated web server, through which the User may adjust, control and monitor the Device.