1. A constraint-based speech recognition system for use with a form-filling application employed over a telephone system, the system comprising: an input signal comprising: a) speech input, and b) non-speech input of a type generated by a user via a manually operated device; a constraint module operable to: a) access an information database containing information suitable for use with speech recognition, and b) generate candidate information based on the non-speech input and the information database, the candidate information corresponding to a portion of the information; and a speech recognition module operable to recognize speech based on the speech input and the candidate information.