19. The system according to claim 18 , wherein the voice server constructs the voice database with repetition of voice calls between the transmitting terminal and the receiving terminal.
19. The system according to claim 18 , wherein the voice server constructs the voice database with repetition of voice calls between the transmitting terminal and the receiving terminal. 20. The system according to claim 19 , wherein the voice server further stores text data absent in an already constructed voice database among text data corresponding to the second voice data constituting the voice call between the transmitting terminal and the receiving terminal, in matched form with voice data corresponding to the text data absent in the voice database, for each sentence, each word, and each syllable.