| 摘要 |
PROBLEM TO BE SOLVED: To change a communication mode to another mode during the communication by decoding the tone code signal received from a telephone network line to produce a mode signal during the communication of an image telephone set. SOLUTION: A tone code codec unit 600 produces a tone code to show the mode setting and change in response to the control signal to be sent to a control unit 100. The tone code is sent to the opposite party via a telephone network line 10. The unit 600 decodes the tone code received from the opposite party and produces a mode control signal to send it to the unit 100. The unit 100 controls a switch 510 to connect the telephone network line to a modem 500 and a telephone set 1100. Thus, the communication mode can be changed while a system is calling. For instance, an aural communication mode can be changed to an image communication mode by the key input of an image telephone set of the calling or called side. As a result, the aural communication can be converted into the image communication even during the communication. |
