Qiang and Cox TASK-INDEPENDENT CALL-ROUTING Qiang Huang and Stephen Cox * School of Computing Sciences, University of East Anglia, Norwich NR4 7TJ, U.K. sjc@cmp.uea.ac.uk Abstract Call-routing is the technology of automatically classifying the type of a telephone call from a customer to a business or an institution in order to transmit the call onward to the correct “destination”. Making transcriptions of calls to provide training data for auto- matic routing in a particular application requires considerable human effort, and it would be highly advantageous for the system to be able to learn how to route calls from train- ing utterances that were not transcribed. This paper introduces several techniques that can be used to build call routers from an untranscribed training set, and also without any prior knowledge of the application vocabulary or grammar. The techniques concentrate on identifying sequences of decoded phones that are salient for routing, and introduces two methods for doing this using language models that are specifically tailored for the routing task. Despite the fact that the phone recognition error-rate on the calls is over 70%, the best system described here achieves a routing error of 13.5% on an 18 route task. 1 Introduction The aim of call-routing is to provide an “automated operator” to deal with incoming tele- phone calls to a business. A call-router uses speech and language processing techniques to classify a call as one of a small number of call-types, and then transmits it to the appro- priate “destination”. The destination might be another automatic system if the transaction required by the caller is a simple one, or a human operator for a sensitive or complex transaction. For example, in an application where the router receives calls associated with a credit-card account, the utterance “I lost my card” would be routed to LostCard and the utterance “What is my account balance?” to Balance. In this paper, we assume that rout- ing must be done on the basis of a single utterance from the caller i.e. the system has no dialogue facility. Call-routing was pioneered by Gorin and his colleagues at AT&Tfor use in the AT&T network, resulting in a system called “How May I Help You?”. (Gorin, Riccardi, & * Corresponding author. 1