1. A method of automatic speech recognition, comprising the steps of: a) receiving from a user, an utterance in reply to a text message via a microphone that converts the reply utterance into a speech signal; b) pre-processing the speech signal using at least one processor to extract acoustic data from the speech signal; c) identifying an acoustic model of a plurality of acoustic models to decode the acoustic data, using a conversational context associated with the text message; and d) decoding the acoustic data using the identified acoustic model to produce a plurality of hypotheses for the reply utterance.