1. A method of dynamically extending the speech prompts of a multimodal application, the method comprising: receiving, by a prompt generation engine, a media file having a metadata container, wherein the prompt generation engine operates on one or more voice servers; retrieving, by the prompt generation engine from the metadata container, a speech prompt related to content stored in the media file for inclusion in the multimodal application, wherein the speech prompt is an audio phrase played by the multimodal application, wherein retrieving a speech prompt includes retrieving a speech artifact having a grammar rule or a pronunciation rule and wherein retrieving a speech prompt includes retrieving a speech artifact having an XML document; and modifying, by the prompt generation engine, the multimodal application to include the speech prompt.