1. A method for conducting voice communications, comprising operations of: a human operator receiving telephone calls from a variety of remote callers over time; for each particular call from a caller, performing operations comprising: selecting an output voice that exhibits prescribed speech characteristics appropriate to that particular call; the human operator listening to voice utterances of the caller; instead of the operator speaking to the caller, performing operations comprising: the operator selecting target speech content to be conveyed to the caller; the operator directing a representation of the selected target speech content to a speech processing facility; the speech processing facility producing a signal representing an enunciation of the target speech content utilizing the selected output voice; transmitting the signal to the caller.