Abstract: The telecommunications apparatus has telephone terminal devices (3) that are constructed to be operable fully and completely by a connected computer via a telephone exchange unit. The computer (2) generates operating signals for full and complete operation of the telephone terminal devices (3), which are connected with the computer only through the telephone exchange unit. The computer (2) is connected with the telephone exchange unit (1) by means of a standard data link and the telephone exchange unit (1) is equipped so that the operating signals from the computer are converted for transmission in a telephone channel (B channel) connecting the telephone terminal devices (3) to the telephone exchange unit.