Abstract: A mobile telephone user interface that includes a keypad, and which mobile telephone may operate in several different states of operation from the standpoint of a mobile telephone system, is characterized in that a press of a key in a first state of operation activates a first function and in a second state of operation, a second function. For example, when the telephone is in a call conversation state, a press of a SEND key activates a volume adjustment, or when the telephone is in a ready state, a press of an END key activates deletion of characters from a display. The present invention preserves the versatility of a user interface while simplifying a telephone by decreasing the number of keys.