9. A system comprising: a processor; a non-transitory computer-readable storage medium having stored therein instructions which, when executed by the processor, cause the processor to perform a method comprising: constructing an unweighted grammar permitting all letter sequences that map to speech input; generating keypad constraints using the unweighted grammar and a weighted statistical letter model trained on a database of words; receiving non-speech input constrained by the keypad constraints; and recognizing the speech input and the non-speech input using the unweighted grammar and the weighted statistical letter model.
13. The system of claim 9 , the non-transitory computer-readable storage medium having stored therein further instructions which, when executed by the processor, cause the processor to perform a method further comprising: generating a final letter string based on the database of words.