1. A method performed by data processing apparatus, the method comprising: receiving information relating to (i) a communication device that has received an utterance and (ii) a voice associated with the received utterance, the received information relating to the communication device including a geographic location of the communication device; comparing the received voice information with a plurality of voice signatures in a comparison group, the comparison group corresponding to a plurality of different individuals location of the communication device, wherein the comparison group includes at least one voice signature for each different identified individual; attempting to identify the voice associated with the utterance as matching the voice signature corresponding to one of the individuals in the comparison group; if the attempt to identify the voice associated with the utterance is unsuccessful, iteratively repeating the attempting to identify the voice associated with the utterance using a modified comparison group, the modified comparison group corresponding to a different geographic region than was used in a previous attempt to identify the voice associated with the utterance, the iterative repeating of the attempting to identify the voice associated with the utterance continuing until the voice associated with the utterance is successfully identified; and providing the communication device with access to one or more resources associated with the individual whose voice signature matched the voice associated with the utterance.