1. A method comprising: starting an automatic speech recognition session for a phone call initiated from a communication device; determining that the communication device is associated with a plurality of users; identifying a group of selected speech recognition models comprising a speaker independent model and a plurality of speaker dependent models; recognizing an utterance received from a particular user in the plurality of users using each model in the group of selected speech recognition models in parallel, to yield a group of recognition results; selecting a dominant speech model from the group of selected speech recognition models using a heuristic search algorithm, to yield a selected dominant speech model, wherein the dominant speech model is an efficient model in the group of selected speech recognition models; and continuously using the selected dominant speech model to recognize speech received from the particular user for a remainder of the automatic speech recognition session.