The user calls the Directory Assistance number to request telephone numbers of individuals or establishments.
Operators then respond with the appropriate listed number.
This service was originally provided by operators who used the paper method, i.e. telephone directory books, to find the desired listing. Printed telephone directories for operators were replaced by computer systems in the 70's. Directory Assistance Operators keyed in sufficient name and address information for the computer to retrieve the listing and display it on a CRT monitor. Replacing the books with computers reduced the search time needed to find the listing. Today, more of the functions performed by the Directory Assistance operator are being replaced by computers equipped with speech recognition capability.