The control device of a communication system of an aircraft having a predefined number of communication channels comprises a processing unit and one or more sets of buttons each associated with a communication channel. The number of sets of buttons is less than the predefined number of communication channels of the communication system. The device comprises a set of call buttons comprising at least one transmission button, and a display area on a display screen, this display area being associated with the set of call buttons. The processing unit is configured to display an indication in the display area associated with the set of call buttons when the communication system receives a call on a channel with which no set of buttons is associated and to select this channel for transmission following an action of a user on the transmission button of the set of call buttons.