1. A voice access system for enabling voice access to an enterprise data system, comprising: a voice recognition unit, including: a processor; a telephony interface coupled to the processor to enable the voice recognition unit to receive user input via a telephone connection; and a network interface coupled to the processor to enable the voice recognition unit to be linked in communication with the enterprise data system via a computer network; and a memory in which a plurality of machine executable instructions are stored comprising a plurality of software modules; and a speech processing server, including: a processor; a network interface coupled to the processor to enable the voice recognition unit to be linked in communication with the voice recognition unit via a computer network; and a memory in which a plurality of machine executable instructions are stored comprising a plurality of software modules, wherein the software modules when executed by the processors of the voice recognition unit and the speech processing server interact with each other to perform operations comprising: enabling a user to establish a telephone connection with the voice recognition unit; enabling the user to request an ad hoc query be performed against data stored by the enterprise data system using a spoken natural language query; determining query criteria corresponding to the ad hoc query request by the user; sending the query criteria to the enterprise data system; receiving data from the enterprise data system based on the query criteria; providing feedback data corresponding to data received from the enterprise data system in a verbal format to the user via the telephone connection.