Mechanized directory assistance

A mechanized directory assistance system for use in a telecommunications network includes multiple speech recognition devices comprising a word recognition device, a phoneme recognition device, and an alphabet recognition device. Also provided is a voice processing unit and a computer operating under stored program control. A database is utilized which may comprise the same database as used for operator directory assistance. The system operates as follows: A directory assistance caller is prompted to speak the city or location desired. The response is digitized and simultaneously inputted to the word and phoneme recognition devices which each output a translation signal plus a probability level signal. These are compared and the highest probability level translation is selected. The caller is prompted to speak the name of the sought party. The response is processed in the same manner as the location word. In the event that the probability level fails to meet a predetermined standard the caller is prompted to spell all or part of the location and/or name. The resulting signal is inputted to the alphabet device. When translations are obtained having a satisfactory probability level the database is accessed. If plural listings are located these are articulated and the caller is prompted to respond affirmatively or negatively as to each. When a single directory number has been located a signal is transmitted to the caller to articulate this number. The system also includes provision for DTMF keyboard input in aid of the spelling procedure.