A telecommunications service or application has associated with it a set of exceptions which, in effect, define a set of matchable inputs from a user and corresponding answer functions to be performed in the event of the particular input. An input user text message (50) is tested against a list (51) of exceptions sequentially until a match is found, and then the corresponding answer function is executed. The matching process, inter alia, divides the input text into one or more parts, and information derived from or associated with one part of the input text is used together with information derived from or associated with another part of the input text (or a part of a previous input text) to control the response of the system to the input text (such as the response to be provided to the (user). For example, attributes associated with different identified parts of the input text are cross-referenced to see if the different parts of the input text have any attributes in common.