Abstract: A telephone system that allows multiplexing and demultiplexing plural group calls through simple operations is provided. The telephone system includes a conference trunk creating unit that creates a conference trunk as required and has a multiplexing/demultiplexing special number table prestoring a multiplexing special number and demultiplexing special number corresponding to plural group calls. After plural group calls start, if the multiplexing special number is input, a control unit causes the conference trunk creating unit to create a large-conference trunk, switches and connects the voices of plural group calls corresponding to the multiplexing special number to the large-conference trunk and starts the multiplexed group call.

Abstract: A telephone system that allows multiplexing and demultiplexing plural group calls through simple operations is provided. The telephone system includes a conference trunk creating unit that creates a conference trunk as required and has a multiplexing/demultiplexing special number table prestoring a multiplexing special number and demultiplexing special number corresponding to plural group calls. After plural group calls start, if the multiplexing special number is input, a control unit causes the conference trunk creating unit to create a large-conference trunk, switches and connects the voices of plural group calls corresponding to the multiplexing special number to the large-conference trunk and starts the multiplexed group call.

Abstract: In an improved image data transmission system, an image data partitioning unit is provided at the transmitter section to partition an input image data into a predetermined number of picture elements (blocks) so that same picture elements of the image data can be subject to source image encoding and forward error correction encoding. At the receiver section, picture elements in each of the data blocks are subject to error correction decoding and source image decoding. The receiver section is provided with an image data interpolator which works, when an transmission error is detected, to interpolate with a substitution data the data in a block in which the error has been detected or data in other block to which the error has been propagated as it is. After the interpolation, a reconstructed image data is delivered.