Mercedes-Benz SLK-CLASS Operator's Manual page 7

Placing a "911" emergency call using
audio head unit with the phone
unlocked
Press h button to switch to
telephone operation.
Enter 911 using the number keypad on
the audio head unit.
Press s button for dialing to begin.
DIALING appears in the audio display
while the telephone establishes the
connection.
Wait until the emergency call center
answers, then describe the emergency.
Controls in detail
Audio system
245