PURPOSE: To inform a name of a caller or a password to a callee at the time of calling from a public telephone equipment in an ISDN network.

CONSTITUTION: A card reader part 1 reads out simultaneously a prepaid card in which the remainder frequency being charging information and one of the own name and a password are registered separately in advance by a user, at the time point when it is inputted. An outgoing message constituting part 2 inserts data read out of a card reader part 1 into an calling sub-address element of a call setting message for transmitting it to the other party, and sends it out to an ISDN network 10 through an LAPD 4 and a S interface 5.