I'm not going to lie, I saw these in movies. But I know what it is.... It is a a telephone switchboard. The calls were connected manually, yeap, one by one... In the early days of telephony, through roughly the 1960s, companies used manual telephone switchboards, and switchboard operators connected calls by inserting a pair of phone plugs into the appropriate jacks. Can you believe that? And if they wanted the could hear every call . Do you remember now?
Please SHARE if you remember or knew what it was....