In the days before modern phone systems affluent Home Owners had these fancy intercom phones in there homes

 Since the late 1930's  before we had all the fancy music intercoms and business phone systems and other means of convenience to contact people  in the more affluent homes  they had there own in house private phone systems  to talk to the front door or patio from a bedroom or kitchen etc. Primitive as they where the sound was very good quality and some even interconnected to the individual land line  phone which back then  you had to be affluent to have your own individual phone number and line as most people where on party lines.

This particular unit appears to have been made by Northern Telephone in the 1950's  which is still in business  some systems are still working to this day This particular phone was in the garage of a very large home designed by Frank Loyd Wright in Pittsburgh Pa.