A communication system, comprising: a plurality of patient communication devices, each device comprising a patient speaker/microphone unit, and a speech communication initiation unit; a room controller connectable to said plurality of patient communication devices using a communication bus which comprises distinct electrical wires, at least one of the distinct electrical wires forming a data line and a different distinct electrical wire forming a speech line; wherein the communication system is connectable to a nurse communication device, the room controller and each patient communication device being configured to communicate data over said data line and to enable speech communication over said speech line, the data communication being based on a serial protocol using frames of data, each frame comprising an address of a patient communication device relevant for data in that frame, and active/inactive information pertaining to the relevant patient communication device; wherein the patient speaker/microphone unit can be set in an active or inactive mode depending on the active/inactive information addressed to the corresponding patient communication device, and wherein the speech communication initiation unit is configured to send an initiation signal to the room controller over the data line for requesting speech communication with a nurse, and wherein the room controller is configured to set the active/inactive information to active for the relevant patient communication device once the request has been approved by the nurse, and to establish a speech communication link between the nurse communication device and the relevant patient communication device over the speech line. a plurality of patient communication devices, each device comprising a patient speaker/microphone unit, and a speech communication initiation unit; a room controller connectable to said plurality of patient communication devices using a communication bus which comprises distinct electrical wires, at least one of the distinct electrical wires forming a data line and a different distinct electrical wire forming a speech line; wherein the communication system is connectable to a nurse communication device, the room controller and each patient communication device being configured to communicate data over said data line and to enable speech communication over said speech line, the data communication being based on a serial protocol using frames of data, each frame comprising an address of a patient communication device relevant for data in that frame, and active/inactive information pertaining to the relevant patient communication device; wherein the patient speaker/microphone unit can be set in an active or inactive mode depending on the active/inactive information addressed to the corresponding patient communication device, and wherein the speech communication initiation unit is configured to send an initiation signal to the room controller over the data line for requesting speech communication with a nurse, and wherein the room controller is configured to set the active/inactive information to active for the relevant patient communication device once the request has been approved by the nurse, and to establish a speech communication link between the nurse communication device and the relevant patient communication device over the speech line.