The Voice Operated Intercept Service (VOIS) automates the called-number Operator Number Identification (ONI) function in the New England Telephone Company call intercept system. The system makes use of automatic speech recognition (ASR) devices that were commercially available at the time of deployment in early 1990. The ASR devices are used whenever a caller does not respond by DTMF. Initially, VOIS handled 20,000 calls per day, coming from nearly 200 end-office switches: calls that would previously would have been routed to intercept operators. The older switching technology that required ONI for the intercept service is now essentially phased out. After its three years of deployment in the telephone network, VOIS has processed about 9 million calls. Its effectiveness has remained essentially the same throughout the three-year period: Speech recognition has been employed in 45% of those calls that are successfully automated. Traffic to ONI operators has been reduced by 85%. Calls for which ASR results do not meet predetermined criteria are forwarded to an ONI operator. Analysis of a speech database collected after deployment suggests ways in which the process by which ASR results are accepted could have been modified to increase the proportion of automated calls.

Keywords: Automatic Speech Recognition, Speaker-Independent ASR, Telephone Operator Services, Operator Number Identification, ASR Error Detection