PURPOSE: To allow an unskilled user to make a proper use of various functions equipped with the system selecting functions in an exchange providing the specification functions on telephone terminals to be housed.

CONSTITUTION: When a user of a telephone terminal 200 inputs the name of the function by operating a character input means 201 on the telephone terminal, the function selected by the user is discriminated based on the information inputted from the telephone terminal to make a function offering means 101 provide with the corresponding function. In inputting the first letter of the name of the function, the names of all the corresponding function is displayed on a character display means 202 to allow a user to make a selection. A function discrimination means 102 permits a user to select the names of all the functions which are displayed on the character display means in the case of inputting the name of the supporting function for function selection.