See also:

Rejecting or ending a call
► Press the button on the steering wheel. If you are not in the Telephone menu, you can still accept a call. ...

Problems with PARKTRONIC
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Roadside Assistance button
X Press and hold Roadside Assistance button 1 for more than two seconds. This initiates a call to the Mercedes-Benz Customer Assistance Center. The indicator lamp in Roadside Assistance button 1 ...