Linking/integrating traditional video door entry phone with lock to Smartthings


I live in a flat apartment with a traditional video door entry phone that allows me to see and talk to visitors at the downstairs communal maindoor, with unlock mechanism.

Was wondering if there is any gadget that I can use to integrate to my current video door entry phone, or changing it without having to make changes to the downstairs maindoor camera entry panel.

The solutions that I found so far online comes a complete kit, ie video door entry phone and camera kit, eg. etc, but I can’t change the camera downstairs really.