This very early mode speaker phone, or conference phone, is actually a normal telephone with an amplifier built in.
It was made in Italy in the 1940s or 1950s. The handset and dial are of a Siemens & Halske design which dates from the end of the 1930s.
The phone operates on a normal telephone line, but the amplifier needs power from the mains. This specimen runs on 110 volt.
Apparantly not many were made and not many are left. I could find no additional info on this model on the internet.