31. The method according to claim 30, where in the step b) of providing a constrained arrangement of character recognition probabilities comprises eliminating from con sideration at least one character from the first arrangement of character recognition probabilities.
30. In a speech recognition system for recognizing an identifier entered by a user in accordance with a constrained arrangement of character recognition probabilities, the identifier comprising a first plurality of predetermined characters, wherein the characters are selected from a first set of characters, the first set of characters including a first total number of characters, a method of producing the constrained arrangement of character recognition probabilities, comprising: a) providing a first arrangement of character recognition probabilities, the first arrangement of character recognition probabilities encompassing a second set of characters having a second total number of characters and is a superset of the characters of the first set of characters; and b) producing the constrained arrangement of character recognition probabilities by constraining the first arrangement of character recognition probabilities to encompass a third set of characters constituting a subset of the second set of characters, wherein each character recognition probability represents a probability that a first character entered by the user will be recognized as one of the first character and a second character.