The MCS 263 system unit for mounting under the table has been designed for use with the MCS 20 system and allows flexible and discreet installations. It provides a 5-pin XLR connection for microphones and phantom power. A terminal strip allows connecting loudspeakers, up to three buttons such as microphone button, priority button and clear button as well as an LED for microphone on (illuminating) and request-to-speak (flashing). Another terminals strip allows connecting a headphone. External buttons and LEDs can be selected from the customer. The MCS 263 can be used as chairman microphone unit with three buttons as well as delegate microphone unit with one microphone button. The microphone button is used to turn the microphone on or off. A red LED of the microphone itself and a possible external LED indicate the ready-to-speak status of the microphone. In the request-to-speak mode of the discussion system the microphone button is used to enter a request-to-speak. When flashing the possible external LED and the LED ring of the gooseneck microphone indicate the request-to-speak. When the microphone is released by the user of the chairman microphone unit, the flashing LED will illuminate permanently. When pressing the microphone button once again the delegate can deactivate the request-to-speak. If the MCS 263 is used as chairman microphone unit the priority and clear buttons can be connected in addition to the microphone button. The chairman can turn on his microphone independently from the number of open microphones (NOM). With the priority button the chairman can turn on his microphone and mute or clear all activated delegate microphone units, depending on the system configuration. With the clear button all activated delegate microphone units are cleared. Removable mounting clips allow mounting the unit under the table or in arm rests. The unit is powered via the bus cable. As part of the MCS 20 conference system, the microphone system can be employed at any position in the bus network. Depending on the operating mode selected with the chairman unit, the microphone can be turned on via the microphone button or voice-controlled. The microphone unit is connected in a daisy chain. The installation is even more unobtrusive when connecting the MPR 211 with Revoluto technology.