Stock Photo - 1980 - Apartment Door Answering Service (ADAS) eliminates guesswork for tenants. The apartment lobby has a Touch-Tone phone and a building director listing three digit numbers for occupants. To call, Bernadette Potter of Western Electric dials the appropriate apartment number. When her friend recognizes Bernadette voice, she dials the digit which automatically opens the lobby door. ADAS also enables the tenant to answer outside phone calls while talking to a lobby visitor and vice verse simply by putting one or the other on hold, Operating without a lot of extra wires and equipment, ADAS is a product of Western Electric, the manufacturing and supply unit of Bell System. (Credit Image: © Keystone Pictures USA/ZUMAPRESS.com)