Patent ID: 8254887

Claim:
A communication terminal device including a storage unit with an address book having entries where name information for specifying a communication partner, an identification number of the communication partner and characteristic information of a voice of the communication partner, are associated with one another, a display unit for displaying the information registered in the address book based on a display request, and an input unit for inputting a select signal for specifying the communication partner using the information registered in the address book and displayed on the display unit, so as to allow bi-directional voice communication with another communication terminal device having the identification number corresponding to the communication partner specified via the input unit, comprising: a recording unit which records voice signals of the communication partner at a source or a destination, if the identification number of the source or the destination is not included in the address book; an analysis unit which extracts the characteristic information from the voice signals recorded by the recording unit; and a registration unit which updates an entry in the address book for the communication partner to associate the identification number of the source or the destination of the communication partner if the characteristic information extracted by the analysis unit is included in the address book, by displaying on the display unit, a screen to select a first processing for updating the entry in the address book by associating the identification number of the source or the destination of the communication partner with the characteristic information included in the address book, or a second processing for overwriting the entry in the address book by replacing the identification number associated with the characteristic information included in the address book, with the identification number of the source or the destination of the communication partner.