Open the vintage phone and disassemble it. Understand the Rotary encoder.

Found the correct cable that send pulse when the user rotate the disc. There are a lot of examples on the internet.

Found the control of the switch that changes the status from hanged up and picked up.

Studied, with the help of Internet, how the ring bells work. Found that an H-bridge is needed to invert voltage, found that also higher then 5 volts is needed.

Ordered some components online.