PURPOSE: To maintain confidentiality by converting a message from a caller subjected to speech recognition into a character code and ciphering the code based on a password of each called party.

CONSTITUTION: When a called party is absent in an exchange provided with a central office trunk, a CPU controlling each block and a subscriber circuit connected to a telephone set in a called party, a name and a message from a caller to the called party are subjeced to speech recognition with a speech recognition device 15, they are converted into a character code, a ciphering device 16 ciphers the character code by a password corresponding to the name to be recognized and stores the code to a message input/output device 17 and when the called party correctly inputs a password from a telephone set A23 to confirm the message, a password collating device 19 outputs a decoding permitting signal, a decoder 18 receives the signal to output the character information.