1. A computer-readable storage device encoded with computer-readable instructions that, when executed by a computing device, perform a method of call processing using a distributed voice browser, comprising: partitioning a voice browser into separate components, including a parser, a service processor and a session manager, the components of the voice browser located and executing on separate computing machines, wherein the components of the voice browser, located on separate computing machines, are replicated as needed to support increased call volume; providing a media gateway having a plurality of channel processors; instantiating a plurality of Voice Extensible Markup Language (VXML) parsers, each of the VXML parsers being configured to retrieve and parse VXML script representing a telephone service, and wherein the VXML parsers are instantiated in a first computing machine; instantiating a plurality of service processors, each of the service processors being configured to interpret VXML data parsed by the VXML parsers, and wherein the service processors are instantiated in a second computing machine; instantiating a plurality of session managers, wherein the session managers are instantiated in a third computing machine; receiving a call by telephone switch, wherein the telephone switch selects a free channel processor of the media gateway, queries the media gateway to accept the call, and applies the call to the selected channel processor; identifying call processing VXML scripts associated with the received call; identifying a service processor and transmitting the identified VXML scripts to the identified service processor; implementing the telephone service by the service processor by executing the identified VXML scripts; determining a change in call volume during run time; and varying, at run time to support increased call volume, a number of service processors, a number of VXML parsers, and a number of session managers independently in response to determining a change in call volume detected during run time.