In this paper we describe our solutions to the problems faced in building the fully featured auto-attendant application that currently provides telephone access to approximately 50,000 Microsoft employees. The paper focuses on issues that the application developer can address directly. Some of the problems tackled in building the grammar include the handling of homonyms, several people with the same name, and data requiring name normalization. Our voice UI helped with this high perplexity task by providing multiple ways to specify the required employee, including spelling their email address or selecting them from a list of employees. Over 70% of the calls analyzed were successfully completed. The system was built using the Microsoft Speech Application SDK and runs on the Microsoft Speech Server 2004. 1. Overview The system connects people to nearly 50,000 Microsoft employees in North America by phone. Callers speak the name of the employee they want to contact. The system performs confirmation steps and, if successful, connects to the employee, otherwise the caller is connected to the operator. Figure 1 shows some of the possible dialog interactions.