A user enters a numeric string on a standby screen of a cellular telephone (1), and then presses a predetermined function key, the numeric string being obtained by numerical conversion of a keyword related to a piece of registration information, e.g. a destination e-mail address, in accordance with an assignment relationship between characters and numerical keys. In the cellular telephone having recognized the entry of the numeric string and the pressing of the predetermined function key, a database is searched by using as a key the entered numeric string or a character string obtained by character conversion of the entered numeric string in accordance with the above-mentioned assignment relationship, and e-mail destination candidates associated with the numeric string or the character string are extracted and displayed on a display. The user selects a desired destination from among the candidates, whereby an e-mail destination address is selected and called up.