A key feature of all COMAND systems is to provide deep integration between the various functions such as multimedia, navigation and telephony and to also allow multiple presentation and control facilities. An example of functional integration is where other audio sources can be muted when a phone call comes in or when navigation guidance is being given. It is also the case that the main audio system, speakers and microphone are used for all these functions instead of being logically and functionally separate. With regard to multiple presentation and control facilities, COMAND based vehicles allow steering wheel controls to be used alongside the main COMAND buttons and controller and COMAND related status information and instructions can be displayed in the instrument cluster in addition to the main COMAND display. On vehicles with a factory fitted Mercedes-Benz rear seat entertainment system, this also provides integration with the COMAND system, allowing for instance the rear seat displays to show content from the COMAND TV receiver or to play out the rear DVD audio over the car's surround sound system.